Abstract: A large amount of emulsion which decreased the extraction rate of peanut oil was easily formed when peanut oil was obtained by aqueous extraction,and it might be closely related to the characteristics of its raw materials.This paper researched the effects of peanut types,peanut paste storage conditions and peanut skin on the extraction rate of peanut free oil.This paper compared the free oil extraction rate of four different peanuts and analyzed the emulsification properties of their proteins by measuring peanut protein simulated emulsion.Peanut oil was extracted with 0.5% Tween 20 solution(water as a reference)followed by the peanut paste at different temperatures for 0,2,4,6,8 d.The results showed that the Dabaisha(old)peanuts had the highest free oil extraction rate obtained by water,and their proteins had good emulsification properties.Whether using water or 0.5% Tween20,the appropriate storage time(2~6 days)and storage temperature(room temperature or 37 ℃)could promote the accumulation of oil and finally improve the free oil extraction rate. However,as the storage time went on,the effect of Tween-assisted demulsification decreased. Low temperature roasting followed by removal of peanut skin greatly reduced the yield of free oil(P<0.05).