Abstract: In order to improve detection methods and detection efficiency for encoders, an automatic detection system for encoder errors is brought forward based on the analysis of encoder error detection status. The working principle and the design of hardwares and softwares for the proposed system are introduced in detail. Experimental results show that the automatic detection system can realize the positioning of measuring points, data acquisition and error analysis for encoders automatically by using motion control and all closedloop control in taking a 24 bit incremental encoder as the feedback element. It has the positioning accuracy of 2″ and can be used to detect the errors of all kinds of encoders less than 18 bits. In the experiment, the detection efficiency of the automatic detection system is 6 times as high as that of the standard device, which proves the feasibility of the project.