In order to ensure the stability of the operating temperature of a butterfly shaped semiconductor laser， a temperature control system based on improved particle swarm optimization （PSO） was proposed. The internal TEC （Thermo Electric Cooler） of the butterfly shaped semiconductor laser was used as the controlled object to calculate its transfer function. A temperature control system simulation model was built in Simulink simulation tool to analyze the impact of temperature on the laser operation. Based on the improved PSO algorithm to optimize PID （Proportional Integrated Derivative） controller parameters to achieve good temperature control effect， the experimental results showed that optimizing PID controller parameters through the improved PSO algorithm could ensure the safe and stable operation of the laser in the temperature control circuit， and achieve the goal of high stability and fast response speed of the laser TEC temperature control system. The maximum temperature fluctuation error within two hours was 0.13 ℃， and temperature stability increased to 0.52%.