Abstract: Effect of operation conditions on desahing of Xingjiang crudes was studied on pilot test apparatus. Optimum conditions were determined for crudes from two main fields. It was observed that there are apparent discrepencies between these two sets of data. It is viscosity-temperature dependency of crudes that mainly affects the selection of operation parameters. The higher resin and asphalt the crude oil contains, the more demulsifier is needed. Mechanism of influnces of properties on desalting efficiency is discussed.