This paper proposes a thermal network parameter estimation method for insulated-gate bipolar transistor (IGBT) modules using the junction temperature cooling curve. The proposed method finds the RC parameters of a fourth-order Cauer network by establishing a relationship between RC parameters and time constants of junction temperature response curves. Experimental tests are performed to validate the accuracy of the developed method. Results show that the difference of total thermal resistance between the proposed method and IEC standard is below 2%. Advantages of the proposed method over the existing methods are that the proposed method does not need 1) to know the power loss information of IGBT and 2) to heat the IGBT module up to thermal steady state. In addition, we show that the identified RC parameters can be used for condition monitoring and junction temperature estimation.