Abstract: This paper carries out freezing point test for Tarim Oil, Kazakhstan Oil and North Xingjiang Oil mixed in different proportions, and analyzes the impact of different additive volumes on oil freezing point at different heat treatment temperatures and the same heat treatment temperature, and obtaines the influence law of different mixing proportions, heat treatment temperature and additive adding volume on the freezing point, i.e. repeating heat treatment temperature higher than 40 ℃, adding volume controlled at 25 mg/kg. Based on the results of laboratory studies, it carries out freezing point tests for the sample taken from the mixed crude oil in Western Crude Oil Pipeline, and obtaines the change situation of the freezing point of crude oil after acting by complex thermal history and shear history along the pipeline with additive and without additive. The results show that at present, just heater starting operation at the initial station alone can ensure safety operation of the pipeline, and that safe and economic operation schemes can be developed based on the characteristics of the pipeline.