Uncooled infrared focal plane array (IR-FPA) assembly is power device. The temperature of uncooled IR-FPA assembly will be risen up along with working time, which directly affect the performance stability of the uncooled IR-FPA assembly. A design based on propertional integral (PI) control which is composed of thermo-electric cooler (TEC), PI controller, Pt-100 temperature sensor is capable of measuring and controlling temperature, and the temperature controlling circuit can keep the temperature change of the uncooled IR-FPA detector between 25 ℃～15 ℃. The precision of controlling is±0.1 ℃, so that the temperature controlling system based on PI control can ensure the uncooled focal plane array detector work in the temperature of high stabilization and precision without noise in addition.