The contact pressure within PP-IGBT devices is unevenly distributed due to the height tolerance dispersion of the packaging materials during the production process, but the existing contact pressure measurement method is intrusive and difficult to be applied in online state monitoring, a modeling method for contact pressure measurement of PP-IGBT devices based on ultrasonic non-invasive technology is proposed. Firstly, the two-dimensional ultrasonic simulation model of PP-IGBT device is established based on the package material size. Secondly, the ultrasonic response of contact interface under different pressure is studied by using equivalent displacement of contact surface. Finally, the simulation results are verified by a single chip device pressure test. The results show that the maximum error between simulation and experimental results is about 4.35%, and ultrasonic reflection amplitude decreasing with the increase of contact pressure is verified. The research results provide a theory for the application of ultrasonic technology to the accurate measurement of contact pressure distribution within PP-IGBT devices, which is of great significance to the safety of system operation.