GaN devices usually operate at high junction temperatures, so it is crucial to monitor the temperature of the device as well as thermal management. Traditional methods for monitoring junction temperature include physical contact and optical methods, but the practical application of these two methods is often limited by the packaging of the device as well as the size of the module, so the best way to monitor the junction temperature is the electrical method, which utilizes the temperature-sensitive electrical parameter (TSEP) to infer the junction temperature. Currently, the TSEP measurement method is more mature for Si-based devices, but there is less research on GaN-based devices, especially the short-circuit (SC) current has not been related work to study it. In this thesis, the SC current is utilized as TSEP to measure the junction temperature, and find that this method has good linearity and sensitivity, which is suitable for monitoring the junction temperature of the device in circuit applications, which provides an alternative method for junction temperature measurement of GaN devices.