Abstract: Augmented reality system which is based on ARToolKit development kit.Since the image segmentation threshold is fixed, when the scene changes greatly, it cannot achieve augmented reality. In order to solve this problem, we put forward the calculation of the image threshold for real-time image in the video sequence with the minimum error method, when the scene changes, the threshold will change accordingly. In the ARToolKit system we do some augmented reality experimental research on marker rotating case. The result shows that the method can still achieve augmented reality when the scene changes a lot, which proves the validity and real-time of the method. Thus, it can improve the overall performance of ARToolKit enhanced reality system.