The invention provides a non-cryogenic oil absorption separation method for a mixture of low-carbon hydrocarbons, which is used for separating the mixture of the hydrocarbons from gas during production of olefins from methanol. Methane / hydrogen can be separated from heavy components, namely C2 and above by absorbing fractions of the C2 and above by adopting two or more strands of absorbing agents. According to the method disclosed by the invention, an absorbing agent separating tower is increased before a demethanization tower, one strand of material flow, which is separated from the tower is taken as a main absorbing agent of the demethanization tower for absorbing the C2 and C3, the strand of the absorbing agent is the mixture of the fractions, which is from the former system and needs to be separated, and circulation is not required. The second strand of the absorbing agent of the demethanization tower is from a system including a depropanization tower and a debutanization tower, and the absorption effect is further enhanced. Compared with the prior art, the method can greatly reduce the using quantity of the circulating absorbing agents; moreover, the multiple strands of the absorbing agents are adopted, equipment investment and energy consumption are significantly reduced, the recovery rate of ethylene and propylene is further improved; and furthermore, the flow is simple, the operation cost is low, and the operation is safe and reliable.