For the issue of structure- light auto- scanning measurement system parameters calibration, a high precision calibration method based on coplanarity is proposed, and the internal and external parameters of the system are calibrated simultaneously. The camera model and the system model are established. The intrinsic and extrinsic parameters of camera and the planar chessboard target are calibrated with the Zhang method. In view of the system calibration requirements, the target location planning is completed, and the position and orientation of the target is changed in the same light plane to obtain coplanar light stripe center points. The light plane equations are solved separately in several light stripe center point data groups. Considering that cross lines of several light planes are more than one, an optimized objective function is defined to solve and optimize the galvanometer shaft expression in the camera coordinate system. The transformation matrix from galvanometer coordinate system to camera coordinate system is obtained. The calibration process is simple, and computation of the algorithm is small. It′s suitable for calibration on spot. Results show that the high precision calibration method is able to meet the requirement.