The invention provides a transmission device for a hybrid power vehicle and relates to a transmission device. The transmission device comprise an output shaft system part, an intermediate transmission part, a driving motor and a reverse gear shaft system part, wherein the output shaft system part is used for driving the vehicle; the intermediate transmission part is used for transferring power output by an engine of the vehicle or/and a driving motor to the output shaft system part according to various transmission ratio forms, wherein the intermediate transmission part is in transmission connection to the engine of the vehicle; the driving motor is used for independently driving the vehicle or jointly driving the vehicle with the engine of the vehicle, wherein the driving motor is provided with a motor output shaft; and the reverse gear shaft system part is used for transferring the power output by the driving motor through the intermediate transmission part or/and directly transferring the power output by the driving motor to the output shaft system part, wherein the reverse gear shaft system part is coaxially connected to the output shaft of the driving motor. The basic function of the transmission device which can provide various transmission ratios is effectively realized while the size of the transmission device is further reduced.