To improve the measurement accuracy of the binocular vision system, the binocular vision system error model is established. Meanwhile, the influence of camera calibration accuracy and the lens parameters and structural parameters of vision system on system accuracy are analyzed. And the rationality of the theoretical analysis is verified by experiment. The experiment results show that, when placing calibration targets at the different depths relative to the camera of the entire field of view, the system accuracy can be improved effectively by increasing the number of calibration image. The system error can be reduced by increasing the baseline distance in the premise of effective field of view. And the system has higher measurement accuracy while the angle values between the baseline and the optic axial range from 55o to 70o.