In order to calibrate the joint angle of industrial robot quickly and accurately, a calibration system of industrial robot based on point constraint is designed. The principle is to calibrate the laser beam to irradiate in the center of the first PSD (Position Sensing Device) and reflected to the second PSD center in four positions by controlling the laser pointer on the end-effector of the industrial robot, and obtain four groups of joint angles, and calculate the linear equations of the position and orientation of the end-effector by the joint angles respectively. According to the fact that the intersection point of each linear equation is the same point (point constraint), the Isqnonlin function is used to search the angle deviation of industrial robot joint. Based on the model of calibration system, six calibration experiments are carried out with ABB Company's IRB120 industrial robot as the experimental platform. The experimental results show that the industrial robot calibration system based on point constraints can calculate the J2~J6 joint angle deviation of the industrial robot quickly and accurately, and the joint angle J1 cannot be calibrated temporarily because of the transformation matrix.