Abstract: Relationship of pressure with the change of temperature when oil heated in closed pipe section expands is analyzed. Based on two assumptions, crude oil is fully filled within the closed pipe section and no oil soluble air. and with oil nonsoluble air within the section, mathematical models are built up. Theoretical calculation results and measured data on pressure change in Alataw Pass Pumping Station of Sino-Kazakhstan Oil Pipeline are compared and analyzed. Empirical equations of two models are obtained by means of data fitting, which provides theoretical foundation in determining winter set temperature of electric tracing for Alataw Pass Pumping Station.