An input shaft structure for connecting a motor (4) and a gearbox (1) is provided, wherein the input shaft structure comprises a main shaft (5), an input end of the main shaft is located within the motor, and is connected to a rotor of the motor, an output end of the main shaft is located within the gearbox, and is connected to a driving gear (2) of the gearbox, and all of the two ends and an middle portion of the main shaft are provided with a bearing (6, 9, 14) to perform axial positioning, wherein a hub (2-1) of the driving gear extend toward two sides, and an inner bore of the hub matches with a shaft diameter of the main shaft to perform radial positioning, to ensure a concentricity of the driving gear and the main shaft. The motor shaft and the input shaft of the gearbox are designed as an integral input shaft, which reduces the entire axial size of the power section, facilitates the layout of the entire vehicle, and has a smaller weight. The two ends of the driving gear are added radial positioning, to ensure a concentricity of the driving gear and the main shaft, which improves the stability of the system.