To improve the heat dissipation performance of surface light source, a 12 mm thickness active ultrasonic micro-water mist heat dissipation module is made, based on the droplet atomization mechanism principle. The heat dissipation principle for this design is that, liquid water is oscillated into tiny droplets by ultrasonic atomizing. Then droplets are directly injected onto heat source surface, forming an ultrathin liquid film. The ejected droplets spray also produce forced convection and evaporation vaporization with secondary nucleation effect to achieve rapid cooling. With a special design of absorbent medium, the internal liquid circulation is achieved to enhance the heat dissipation effect. In this article, the heat dissipation performance comparison of fin fan and micro water mist cooling module are tested by using thermistor temperature acquisition system. Under the same size and power consumption conditions, the temperature rise of the micro-water mist cooling module is 7.8 ℃ lower than fin fan module. Compared with fin fan module, the heat dissipation performance of our design is increased by 12.9%. At the same time, this new design achieves the requirements of low cost, no noise and high heat dissipation performance.