Under the conditions of different temperature and pressure,we measured the viscosity of the crude oil of Tahe oil field and its mixture that the watercut and gas content are different with hightemperature and highpressure viscosimeter.The relationship between the viscosity of the crude oil and its mixture and the temperature or the pressure was also discussed.It has been indicated that the viscosity and temperature character fit to exponential law,the viscosity is linear transformation with the pressure.The gas content strongly influences the viscosity of the crude oil.The viscosity of the gas oil has a minimal value varying with the pressure,and the viscosity of the waterbearing oil has a maximal value varying with the watercut.