Abstract: Starting from ethylenediamine and methacrylate, 2.0 G starburst dendrimers were synthesized by twice Michael reaction and amidation. The starburst dendrimers were then grafted by reaction of epoxy ethane/epoxypropane co-polyether with hydroxyl value of 60 mgKOH/g and epoxy chloropropane, a chain extender, to prepare a new type of multi-branched demulsifier. The 2.0G starburst dendrimers were characterized by IR and potentiometric titration. The demulsifier were characterized by IR and the demulsification performance was evaluated. The demulsification results for a simulated crude oil emulsion of PL19-3 WHPD platform show that the dehydration ratio can reach 90% at 50 ℃，dosage of demulsifier 90 mg/L and dehydration time 30 min. Compared with the existing demulsifier under simulated field conditions, the new demulsifier exhibits a better performance. The oil content in the separated water is 20.3 mg/L, and the water content in the oil is below 0.5%.

Key words: ethylenediamine, methacrylate, dendrimer, epoxy chloropropane, demulsifier