To resolve the difficulty and low efficiency problem of camera calibration for large-scale vision system, a fast calibration method for camera defocus based on phase shift coding circle is proposed. Firstly, the feature points are extracted in the defocused state by using the phase shift coding circle. Secondly, the target function of monocular camera is constructed through utilizing spatial location information given by the calibration target, and then make use of the nonlinear least square method to solve the internal parameters of the camera. Finally, by establishing the optimization function of the binocular system, the external parameters of the camera system are solved. This method does not need to move the camera or target, and can complete the rapid calibration of the large-scale vision system camera in the defocused state by shooting 3 phase-shift circle images. The experiment results shows that the deviation of the calibrated focal length is less than 0.5%, and the maximum inverse projection error is 0.33pixel, which solves the difficult and low efficiency problems of large-scale vision system camera calibration.