OptiTrack system was the most advanced optical motion capture system in recent years. Camera calibration was an indispensable part of optical motion capture. Its function was to convert 2D data obtained by each camera into spatial 3D data by multiple cameras. The mean error reflected the numerical relationship between the system coordinates and the world coordinates of the measurement area, so the mean error was related to the measurement accuracy of OptiTrack system directly. In this paper, the influence of average calibration error on measurement stability and accuracy was obtained by repeated calibration and sampling under control variables.