Turbine flow meter is a very significant measuring instrument. As an important flow meter, turbine meter is widely used in many fields for its high accuracy, good repeatability, small size and light weight. However, with the viscosity of the measurement fluid increasing, the measured variation of the linearity becomes bad, which makes great influence on the meter factor. In this paper, the experiment on the viscosity impact of turbine flowmeter's performance was completed by adjusting the temperature of the mixture of diesel and lubricants, i.e. changing medium viscosity. And the methods of computational fluid dynamics (CFD) numerical simulate were used to research the accuracy of the turbine flow meter in the same conditions. According to the comparison of the two methods, the influence of the turbine flowmeter’s precision measuring fluids with different viscosities was analyzed. It provides a data basement for improving the measurement accuracy of a certain viscosity fluid in the future.