The uncooled optical readout infrared imaging system altering the infrared image directly into a visible image is becoming a hotspot of research recent years. How to reduce the volume and improve the quality of infrared imaging is a key problem of the optical readout infrared thermal imaging system. In this paper, an reflective readout method of infrared imaging systems is presented, by which reduce the volume of the system for about 30%, improve the uniformity of the infrared image, the minimum detectable angle can be decreased by 1.3×10-5deg than knife-edge filter method. The result of experiment is basically consistent with the theory analysis, experimental results indicate that the NETD of this system can be reach 173mK. Compared with traditional methods, the reflective optical readout method can effectively improve image quality.