The present invention discloses a bidirectional mechanical converting unit, comprising: a main shaft; a driving mechanism, which including a driving means and a reversing means which are coupled to each other; and a rotation means for inputting torque, an rotation axis of the rotation means being coaxial with the main shaft, the rotation means and the driving mechanism being coupled to each other, and the driving mechanism delivering the torque to output at the main shaft at a predetermined direction, no matter in which direction the rotation means rotates; wherein the predetermined direction can be switched via the reversing means. The present invention is simple structured, not only can efficiently utilizes the movements of the rotation means in either way, but also can switch the rotation direction of the output shaft conveniently upon demand, with easy operations.