In the space scene, IRST work process is that system scans the certain field according to the prior information, and transmits image **data** to the infrared image real-time processing system for processing. Firstly, IRST detects and select suspected tracking target. Then the system which is derived from the automatic detection and tracking method, determines the location and size of the target to be detected, and calculates the moving direction and speed information of the target to the spacecraft platform. Finally, the platform controls the detector to track the moving target and keeps target in the field of the detector. During the process, the platform performs target position correction at any time. The working process of IRST is shown in Figure 1. 