Abstract: A high-stable control system based on the MCU of MSP430 for semiconductor laser is introduced to realize stable, reliable and accurate power output. According to the working principle of semiconductor laser, the controlled constant current source, temperature control system, light power feedback system and protection circuit was designed. It has real-time control, display and reset functions, and provides protection to the laser power. The light power feedback was used to achieve the light power stability. The thermoelectric cooler driven by high-accurate PWM amplifier was employed to control temperature. The light power stability is better than 0.25%.