NOVELTY - Preparing methanol or dimethyl ether propylene, comprises (i) separating starting raw materials, water and components having more than 4 carbon atoms, and reacting; (ii) separating resultant product, returning the aqueous phase into the first reactor, and transferring the gaseous phase of organic hydrocarbon components into a primary fractionating system, and separating 1-2C component, and 3C component; and (iii) directly heating 1-2C component, reacting, cooling the reaction product, and transferring into a gas-liquid separator, and returning gaseous phase as fuel gas into second reactor.    USE - The method is useful for preparing methanol or dimethyl ether propylene (claimed).    ADVANTAGE - The method has high propylene selectivity in the first reactor of greater than 70%, and propylene yield in the second reactor of more than 75%, and simple preparation procedure; does not require ethylene cryogenic fractionation system and low 2 C content components; and simplifies the separating system, and reduces the energy consumption of the separating system.    DETAILED DESCRIPTION - Preparing methanol or dimethyl ether propylene, comprises (i) separating the starting raw materials, water and components having more than 4 carbon atoms, reacting in a first reactor, to produce propylene rich 1-10C hydrocarbon components and water; (ii) separating the resultant product in a separating system, returning the aqueous phase into the first reactor, and transferring the gaseous phase of organic hydrocarbon components into a primary fractionating system, then separating the 1-2C component, and 3C component, and transferring 4-10C components into a gasoline removing tower, separating the component in the tower top to return to the first reactor, and directly using 3C component as product or separating in a propylene tower to obtain propylene and propane; and (iii) directly heating 1-2C component in a second reactor, and reacting to obtain high carbon material having more than 3 carbon atoms as main component, cooling the reaction product in the second reactor, and transferring into a gas-liquid separator, and returning a portion of gaseous phase as fuel gas into the second reactor, and returning the liquid phase into the fractionation system.