To suppress the fluctuation of medium wave infrared laser output power, a kind of power stabilization system was developed by the method of acousto-optic feedback, which consists of acousto-optic modulator, detector, micro-current amplifier and feedback control circuit. According to the experimental results, this system has the ability to suppress the power fluctuation in the range of ± 0.08% and to meet the stable output power requirement of cryogenic radiometer. Different mode can be set easily in software to obtain the different output power of the laser, and the adjust progress will be finished within 2 s by using the incremental PID control algorithm. This function gives users great convenience and solves the problem that one laser can only supply one output power. This system has the advantage of good practicability and innovation.