Absolute positioning accuracy is an important index to measure robot performance. In order to improve the absolute positioning accuracy of industrial robots, a method of positioning error classification based on kinematic calibration and spatial interpolation is proposed. Firstly, the kinematics model of the robot is established based on D-H method, and the error model of the end position of the robot is established by using differential kinematics theory. The kinematic parameters are identified by using the tolerance ridge estimation combined with IGG3 weight factor function. Then, based on the spatial similarity of robot positioning errors, the remaining errors are compensated by the spatial interpolation method. Finally, the proposed method is verified by experiments. The results show that the robot positioning error RMS decreases from 0.812 mm before compensation to 0.049 mm, and the accuracy is increased by 93.97%. This method can effectively reduce the absolute positioning error of the robot and improve the positioning accuracy.