In order to make a laser work stably, a temperature control system with fast control speed, high precision and tunable performance was designed and implemented. ATmega328P was used as the processor in the system. Self-tuning proportional-integral-differential (PID) coefficients was determined by particle swarm optimization. A closed-loop negative feedback PID structure was used to control the temperature of the laser. The results show that, under the control of this system, the laser can reach the target temperature in about 15s. The temperature error after reaching the target temperature is about (±0.01℃). It can be maintained for a long time. The output power of the laser fluctuates very little. The variance is only 568.49μW. The system can effectively control the temperature of butterfly packaging laser.