Abstract: With alkylacrytate, maleic anhydride and composite aliphatic, a series of oil pour point depressant is prepared by initiating polymerization and esterification reaction and an evaluation on its effect is made. The research shows that the effect of the pour point depression is the best when the quality of alkylacrytate: maleic anhydride : composite aliphatic is 2:1:1 and the temperature of polymerization is 90℃. The product can decrease the pour point of crude oil in Nanyang Oilfield by 22℃. Besides, as to Shengli crude oil and Yan'an crude oil, it also works well.