The present invention relates to a dual-motor three-gear variable speed drive device for an electric vehicle. The dual-motor three-gear variable speed drive device comprises a main motor, an auxiliarymotor and a three-gear transmission mechanism, wherein the main motor is a low-speed high-torque motor; the auxiliary motor is a high-speed small-torque motor; a synchronizer of the three-gear transmission mechanism is correspondingly provided with a low-speed gear, a neutral gear and a high-speed gear, respectively. When the synchronizer is located in the neutral gear, the auxiliary motor is separately driven; when the synchronizer is meshed with a fourth gear of the three-gear transmission mechanism, the single-motor drive or the dual-motor drive is selected; when the synchronizer is meshedwith a second gear of the three-gear transmission mechanism, the single-motor drive or the dual-motor drive is selected; five drive modes are implemented in total. According to the dual-motor three-gear variable speed drive device for the electric vehicle, the average efficiency of the dual-motor three-gear transmission motor is 92.31%; with reasonable matching of the drive system gear position and optimization of the drive system, the proportion of the motor operating in the more efficient interval is increased; and the mechanism has high application value is in a commercial vehicle with a large load capacity change.