The invention discloses a high-power density GaN full-bridge LLC power supply module, which comprises an input rectifier module, a GaN power factor correction module and a GaN full-bridge LLC converter module connected in sequence, wherein the GaN power factor correction module performs power factor correction on input of an input high-voltage DC bus DC obtained by the input rectifier module, anda high-voltage bus Vbus and a low-voltage bus Vgnd after power factor correction are obtained; and the GaN full-bridge LLC converter module performs DC/DC conversion on output of the high-voltage busVbus and the low-voltage bus Vgnd, and an output high-voltage bus Vout+ and an output low-voltage bus Vout- are adopted for output. In order to improve the switching frequency of the full-bridge LLC power supply module, an LGA-packaged GaN device is adopted for switching conversion; and in order to improve the reliability, a double-sided layout structure is adopted for layout optimization on a gate drive, the multi-tube parallel GaN device and the voltage bus, the GaN device is ensured to work in a safe area state, high-density power integration and high efficiency are further realized, and the related technology can be widely applied to a high-density AC/DC power supply module.