At present,the threecascadetype refrigeration system is usually used to condense the recovered oil,by which the gaseous oil is normally condensed until the temperature reaches -160 ℃.In the article,the recovery system was improved by adopting twostage cascade refrigeration through increasing the pressure within its security range.The oil condensed temperature can rise to -124 ℃ around.The minimum energy consumption of system was achieved in the possible range by using the entropy analysis on the oil recovery system.The improved system can simplify the device and also reduce the investment and operation cost.