Junction temperature is the key factor that affects the reliability of power semiconductor devices, and accurate junction temperature estimation is of great significance for converter reliability assessment. In this paper, the power device IGBT module is taken as a typical research object, a dynamic estimation method of junction temperature based on case temperature feedback is proposed. Firstly, the junction temperature loss calculation model and Cauer thermal network model of IGBT module are established, and the dynamic digital estimation algorithm of junction temperature is deduced; then, the loss characteristics and thermal response characteristics of the device are tested via the test platform; finally, the estimated junction temperature is experimentally validated using infrared temperature measurement, and the deviation of junction temperature is within ±0.5°C, which verifies the accuracy and effectiveness of the proposed method.