Abstract: Aiming at the problems in Jinghe oilfield,such as big density of crude oil,high nonhydrocarbon and asphaltic components,big difficulty in dehydration and big dosage of demulsifier,the determination on 6 kinds of demulsifier dehydration effect of 20% water cut of heavy oil has been carried out.The dehydration effect of single demulsifier,25-A and HL-1 is superior to other demulsifiers,and the demulsification temperature is 65 ℃.When the concentration of demulsifier is 600 mg/L,the dehydration ratea are 65.6% and62.5% respectively.The dehydration effect of compositional formulation of crude oil demulsifier is obviously better than the single demulsifier.Under the same conditions,the dehydration rate can be higher 15.7%.Through demulsifier concentration and demulsification analysis of the influence factors,the optimal demulsification conditions for Jinghe oilfield are as follows:the demulsifier concentration of 400 mg/L,the mixed compositional proportion of 2:1,demulsification temperature of 80 ℃,and the dehydration rate could reach 94.5% after 10 h settling.