NOVELTY - Separation of 2C/3C light hydrocarbon comprises separately introducing a feed gas and a feed liquor to a 3C absorption tower (1) and a deethanization tower (2); performing gas-liquid separation; removing acid gas and dehydrating; under the action of an absorbing agent, separating the feed gas; under the combined action of reflux and re-boiling gas, separating into tower bottom solution 3C+ and tower top gas 2C-; partially condensing the tower top gas 2C-; feeding one part of the liquid phase in a return tank (3) as an absorbing agent; and taking the other part as reflux.    USE - Method for the separation of 2C/3C light hydrocarbon (claimed).    ADVANTAGE - The integration of an absorption method and a fractional distillation method is more energy saving than the single fractional distillation method. The deethanization tower increases the relative volatility of the light key component and the heavy key component with lower tower pressure, thus reducing the separation energy consumption.    DETAILED DESCRIPTION - Separation of 2C/3C light hydrocarbon comprises:    (A) separately introducing a feed gas and a feed liquor to a 3C absorption tower (1) and a deethanization tower (2), where the feed gas and the feed liquor are formed by compressing at multiple levels, cooling, and condensing;    (B) performing gas-liquid separation;    (C) removing acid gas and dehydrating on the upstream;    (D) under the action of an absorbing agent, separating the feed gas in the 3C absorption tower into tower bottom solution and tower top gas, where the tower bottom solution is 3C+ and a small part of 2C-, the tower top gas is hydrogen, methane, and most part of 2C;    (E) feeding the tower top gas to a downstream system for treating;    (F) feeding the tower bottom solution of the 3C absorption tower and the feed liquor from the upstream in the deethanization tower;    (G) under the combined action of reflux and re-boiling gas, separating into tower bottom solution 3C+ and tower top gas 2C-;    (H) feeding the tower bottom solution 3C+ to the downstream system for treating;    (I) cooling and partially condensing the tower top gas 2C- in a cooling condenser (5);    (J) dividing the tower top gas into a gas phase and a liquid phase in a return tank (3) of the deethanization tower;    (K) feeding one part of the liquid phase in the return tank of the deethanization tower as an absorbing agent into the 3C absorption tower; and    (L) taking the other part as reflux and returning to the deethanization tower.    An INDEPENDENT CLAIM is included for a 2C/3C light hydrocarbon separating system.    DESCRIPTION OF DRAWING(S) - The drawing is a flow diagram of the method for separation of the light hydrocarbon.    Absorption tower (1)    Deethanization tower (2)    Return tank (3)    Cooling condenser (5)    Reflux pump (6)