Abstract: Deep space exploration applications require electronics which are capable of operation at extremely low temperatures (T<40 K). Based on the application requirements of cryogenic temperatures, the effects of cryogenic temperatures from 15 K to 300 K on GaNbased MOSFET were investigated in this paper. The experimental results show that the saturated drain current and threshold voltage are increased as the device is cooled down to 15 K. Both output characteristics and transfer characteristics are enhanced as temperature decreases. The increase of electron migration rate could be the main reason for the shift of electrical parameters of GaNbased MOSFET.