The invention belongs to the loading test apparatus field, and discloses a low-power-consumption duplex transmission shaft loading test mechanism. The low-power-consumption duplex transmission shaft loading test mechanism includes a frame, a left gear case, a left driving motor, an upper center shaft, a right gear case, a harmonic wave gear, a right driving motor and a lower center shaft, wherein the left gear case includes a left box body, a left upper gear and a left lower gear; the upper center shaft and the left upper end rack are used for fixing a left duplex transmission shaft; the right case gear includes a right case body, a right upper gear and a right lower gear; the upper center shaft and the right upper end rack are used for fixing a right duplex transmission shaft; and the harmonic wave gear includes an outer rigid gear, an inner flexible gear, a roller and a wave generator. The low-power-consumption duplex transmission shaft loading test mechanism loads the rotating speed for the duplex transmission shaft through rotation of the left driving motor, and loads a torque for the duplex transmission shaft by adjusting rotation of the right driving motor, wherein according to the principle that speed reduction of the harmonic wave gear can increase the torque, only output of a smaller torque may enable the inner flexible gear and the outer rigid gear to generate a greater torque, so that a greater torque can be loaded on the duplex transmission shaft and the energy can be effectively saved.