The robot arm DH parameter calibration method based on calibration board is proposed,the 7points of calibration board can be sampled by using the end effector in sequence,among which the first 3 points are used to construct the relationship between world and robot coordination system while the other 4 points are applied to establish objective function and error equation. The DH parameter after calibration can be obtained by optimization solution of error equation. At last,the effectiveness of this method is verified through repeated positioning accuracy,the repeated positioning accuracy can be improved from 4. 68 mm to 0. 87 mm. This method has the advantages of simple equipment and easy operation.