The invention discloses a plane constraint error model and a robot self-calibration method. The method comprises the following steps of 1, establishing a robot kinematics model; 2, establishing a robot tail end position error model; 3, establishing the plane constraint error model; 4, driving a robot to measure the constraint plane; 5, identifying kinematics parameters of the robot; and 6, verifying the calibration result. The plane constraint error model and the self-calibration method have the beneficial effects that firstly, cost is low, wherein one calibration block with relatively high precision is needed, and cost not exceeds one thousand while the advanced measuring equipment tends to be tens of thousands or more millions in cost; secondly, a plane accurate spatial equation can be obtained, compared with a traditional plane constraint calibration method, the calibration precision is improved; thirdly, compared with a traditional plane constraint error model, the error model is greatly simplified; and fourthly, the calibration block can be placed in the working space of the robot in any posture, and the difficulty of calibration experiments is reduced.