The invention provides a method for preparing low-energy SLS-structure lipid in a supercritical CO2 state by an ester exchange process. Carbon dioxide can display high solubility when achieving the supercritical state, thereby greatly lowering the mass transfer resistance in the enzyme reaction process, further enhancing the enzyme reaction rate, shortening the reaction period and avoiding the environmental pollution. In the supercritical carbon dioxide (CS-CO2) state, a lipase RMIM is utilized to catalyze the ester exchange reaction on ethyl acetate and first-grade soybean oil to prepare the low-energy SLS-structure lipid, thereby enhancing the ethyl acetate conversion rate. The method optimizes the esterification technological parameters, including enzyme consumption, reaction time, reaction pressure, reaction temperature and the like, and performs the reaction under the optimal conditions, so that the ethyl acetate conversion rate can reach 36.1%.