Abstract: Based on flotherm reliability thermal simulation analysis method, CFD digital prototype of avionics equipment is established.The model is simulated and tested at room temperature, and the temperature data of the two are compared.If the error is less than 5%, the model is correct.The thermal simulation analysis of the model in 70 ℃ environment is done, and the potential component heat dissipation problems and weak links in avionics equipment are obtained.The location and cause of potential faults are pointed out, which can be used to guide the thermal design of avionics equipment and improve the reliability of avionics equipment.