In this paper, a novel GaN-based FS-IGBT is designed, which combines GaN-based Fin-MOS with the conventional material FS-IGBT, and the static and dynamic electrical characteristics of the device are simulated by SILVACO. The results show that the structure has a high saturation current (Ion,sat) density of 155kA/cm2 at 10V gate voltage (Vge), an on-state voltage (Von) of 3.5V, a breakdown voltage (BV) of 1650V, and a switching speed of nanoseconds. The characteristics of the device are analyzed and compared with Fin-MOS. The results demonstrate that the vertical GaN-based device can display both high current density and high breakdown voltage due to the FS layer that adjusts the electric field distribution in the N-drift region. The paper also analyzes the selection of device parameters and feasibility of device manufacturing based on the existing material growth method and device manufacturing technology.