To overcome the shortcomings such as big volume, big noise and limited control precision of the traditional temperature control system of the semiconductor laser, a temperature control system of the semiconductor laser is developed based on the MSP430F449 single chip and DS18B20 digital temperature sensor. In the system, the drive current is controlled by using PWM pulse width modulation and combining with PID algorithm, so the constant temperature of the laser is controlled. The experiment results show that the temperature control precision of the system is better than ±0.1 ℃, and steady temperature condition can be offered for the semiconductor laser.