Abstract: Falling ball method, which measures the viscosity coefficient of liquid, is a basic physical experiment of science and engineering university. Environmental temperature has a significant effect on the fluid density and viscosity. Thus, the temperature is an important parameter in this experiment. In this paper, the falling time in the measuring interval, the terminal falling velocity and the starting position of uniform falling are theoretically calculated under different temperatures and diameters which were given. The results show the law of these parameters varied with the temperature. It provides the basis for the experimenter to select the appropriate experimental parameters, which can reduce the error.