In order to improve the performance of macromolecule polymer demulsifier and enlarge the range of application of nano-material, the nano-Al ₂O ₃ and macromolecule polyether demulsifier TA1031 were grafted by sol-gel method with Al ₂(SO ₄) ₃ and NH ₃·H ₂O. The Nanometer modified demulsifier was analyzed by FTIR, SEM, rotational viscometer and interfacial tensionmeter. The results show that applying nano-Al ₂O ₃ to crude oil polymer demulsifier would greatly improve the performance of the original demulsifier. When the mass ratio of aluminium oxide and TA1031 was 1∶10, the performance of the nanometer modified demulsifier is better, and the ratio of demulsification would be improved about 20%~25%. The time of demulification and dewatering would be greatly shorten, and the demusification mechanism and formation mechanisms of nanometer modified demulsifier was preliminary analysised.