NOVELTY - Separation process for preparing low carbon olefin gas through methanol conversion comprises removing carbon monoxide and oxygen in methanol-to-olefin gas; passing through six separation tanks; and introducing into a high-pressure demethanation tower, deethanization tower, acetylene hydrogenation reactor, ethylene rectifying tower, allylene hydrogenation reactor, propylene rectifying tower for separation, where liquid, which comes out from the bottoms of the first five separation tanks sequentially enters the middle-to-upper part of the demethanation tower.    USE - Separation process for preparing low carbon olefin gas through methanol conversion (claimed).    ADVANTAGE - The process produces polymer-grade ethylene and propylene products and products such as high-purity hydrogen, methane, ethane, and propane.    DETAILED DESCRIPTION - Separation process for preparing low carbon olefin gas through methanol conversion comprises:    (A) removing oxygen-containing compounds, water, and greater than or equal to 4C hydrocarbons in methanol-to-olefin gas, dewatering at the primary level, heat exchanging, removing carbon monoxide, cooling and dewatering, deoxidizing, heat exchanging the low carbon olefin material flow after deoxidizing, washing via alkali and water, mixing the washed low carbon olefin material flow with vapor phase of refluxing tank of ethylene rectifying tower, and mixing the vapor phase of refluxing tank of vapor liquid separation tank and vapor phase of refluxing tank of methane stripping tower into an olefin mixture;    (B) heat exchanging the olefin mixture, dewatering and cooling and guiding the mixture into first separation tank and separating, cooling the gas from the top of first separation tank and guiding the gas to second separation tank, cooling the gas from the top of second separation tank and guiding the gas to the third separation tank, cooling the gas from the top of third separation tank and guiding the gas to the fourth separation tank, cooling the gas from the top of the fourth separation tank and guiding the gas to the fifth separation tank, cooling the gas from the top of the fifth separation tank and guiding the gas to the sixth separation tank, guiding the liquid from the bottom of the first separation tank to the middle-to-upper part of the deethanization tower via pump, guiding the liquid from the bottom of the second separation tank to the middle-to-upper part of deethanization tower, guiding the liquid from the bottom of third to fifth separation tanks to the upper part of deethanization tower, where the liquid from the bottom of the sixth separation tank is the low pressure methane product, and the gas from the top of the sixth separation tank is the crude hydrogen product;    (C) cooling and condensing the gas mixture from the top of the deethanization tower and guiding the gas mixture to the refluxing tank of deethanization tower, taking the liquid phase in the refluxing tank of deethanization tower as backflow and returning the backflow to the top of deethanization tower, where the gas phase in the refluxing tank of deethanization tower is the methane gas phase product, guiding the material flow from the bottom of deethanization tower to the deethanization tower, cooling and condensing the gas mixture from the top of the deethanization tower and guiding the gas mixture to the refluxing tank of deethanization tower, taking the liquid phase in the refluxing tank of deethanization tower as backflow and returning the backflow to the top of deethanization tower, where the gas phase in the refluxing tank of deethanization tower is the gas phase mixture material flow including ethylene, ethane, and acetylene, when acetylene mol content is less than 1 ppm, drying and heat exchanging and guiding the mixture to ethylene rectifying tower, when acetylene mol content is greater than or equal to 1 ppm, guiding the mixture to acetylene hydrogenation reactor, drying and heat exchanging the gas mixture including ethylene and ethane generated at the bottom of acetylene hydrogenation reactor, and guiding the mixture to ethylene rectifying tower, where the product from the bottom of ethylene rectifying tower is ethane liquid phase product, pumping the ethylene product material flow from the top of the ethylene rectifying tower at lateral line and transferring the material flow out of the device, cooling and condensing the gas mixture from the top of the ethylene rectifying tower and guiding the mixture to the refluxing tank of ethylene rectifying tower, taking the liquid phase in the refluxing tank of ethylene rectifying tower as backflow, and returning the backflow to the top of the ethylene rectifying tower, where the gas phase in the refluxing tank of ethylene rectifying tower is mixed with low carbon olefin material flow washed by alkali and water;    (D) the material flow from the bottom of the deethanization tower is the liquid mixture including propylene, propane, cyclopropane, allylene, and allene, when allylene mol content is less than 5 ppm and the allene mol content is less than 10 ppm, pressing, heat exchanging, drying and heat exchanging and guiding to propylene rectifying tower; when the allylene mol content is greater than or equal to 5 ppm and the allene mol content is greater than or equal to 10 ppm, pressing, heat exchanging, drying and cooling and guiding the mixture to the allylene hydrogenation reactor; separating the mixture from the bottom of allylene hydrogenation reactor via vapor-liquid separation tank, mixing the vapor phase from the vapor liquid separation tank with alkali and water washed low carbon olefin material flow; pressurizing the liquid phase from the vapor-liquid separation tank and dividing into two parts; returning one part to allylene hydrogenation reactor and heat exchanging the other part; and guiding the other part to methane stripping tower;    (E) pressurizing and heat exchanging the material flow from the bottom of the methane stripping tower and guiding the flow to the propylene rectifying tower; cooling and condensing the gas phase mixture from the top of methane stripping tower and guiding the mixture to the refluxing tank of methane stripping tower; pressurizing the liquid phase from the refluxing tank of methane stripping tower as backflow and guiding the backflow to the top of methane stripping tower; and mixing the vapor phase from the refluxing tank of methane stripping tower with alkali and water washed low carbon olefin material flow; and    (F) cooling and condensing the gas mixture from the top of propylene rectifying tower and guiding the mixture to the refluxing tank of propylene rectifying tower; and pressurizing the liquid phase from the refluxing tank of the propylene rectifying tower as the backflow and guiding the backflow to the top of propylene rectifying tower, where the gas phase from the refluxing tank of the propylene rectifying tower is the propylene product material flow and the material flow from the bottom of the propylene rectifying tower is the propane product material flow.