The compatibility of asphaltic crude oil with demulsifiers in the electric desalting process was studied in this paper. The test result showed that asphaltene in crude oil causes the raising and abnormal of crude viscosity. Structure and character of asphaltic molecules make them easily gather and associate with each other at the oil/water interface and finally form a viscoelastic interfacial film of great mechanical strength. This not only interferes with the salt transfer from the oil to the aqueous phase, but also hinders the aggregation of the water drops, and thus affects desalting process of crudes. Several kinds of demulsifier series synthesized were used to investigate desalting and dewatering efficiencies in the electric desalting process. It was found that with the same initiator each emulsifier series had got an optimal proportion of propylene oxide (PO) and initiator. There also exists an ideal value of desalting and dewatering efficiency when demulsifiers were polymerized with ethylene oxide (EO) because demulsifiers polymerized with EO will improve its hydrophile-lipophile property. The phenolic resin series were compatible with asphaltic crude in desalting efficiency, whereas the polyhydric alcohol series were more efficient in dewatering efficiency. The recombination of phenolic resin demulsifiers with polyhydric alcohol demulsifiers can give a satisfactory result to asphaltic crude oil in both desalting and dewatering efficiency.