Aiming at the problem that the measurement accuracy of image tracker diverges with external factors， an image tracker detection method based on autocollimator is proposed in this paper. Using the super high angle measurement accuracy of the reference mirror and autocollimator on the back of the image tracker， the fast calibration and detection of the measurement accuracy of the image tracker are realized， and the measurement accuracy is 2.5″. The experimental results show that the measurement accuracy of the image tracker changes with the environmental stress， and the image tracker detection method based on autocollimator can realize the measurement of its accuracy.