The imaging technology of Infrared focal plane array(FPA) detector is a method which converts the thermal radiation of the target into the visible image. It is widely used in target seeking, missile guidance and space exploration, etc. For the requirements of small volume and fast cool-down application in missile guidance, an infrared FPA imaging guidance system was designed, including the catadioptric infrared lens, fast cool-down IRFPA detector, and low noise image circuit. The whole system satisfies the imaging requirements of the missile guidance.