The torque assist system of the present invention includes a torque assist shaft having a first terminating part connected to the input shaft, an outer shaft and an inner shaft rotating independently from the outer shaft; a planetary gear set mounted on the inner shaft exposed to a second terminating part of the torque assist shaft; a clutch being disposed adjacent to the planetary gear set and operated by an external force; and an input gear mounted on the exposed inner shaft of the torque assist shaft and connected to the planetary gear set by the clutch to transmit power to an output gear mounted on the output shaft of the vehicle transmission.