In the application of recognizing the position, tracing and video collecting in real time for a special person, a full-automatic Infrared target recognizing system is designed, which consists of a ARM9 S3C2410 processor, charge coupled device (CCD) imaging units, Infrared filter and 2 degrees of freedom pan tilt. A fast image binaryzation algorithm is designed based on collecting and analyzing Infrared image samples. Through automatic segmentation, fast searching and contrasting, the detection and motion tracing on known Infrared targets in real time are realized. The system is simple, reliable and easy to be embedded in automatic equipments.