The invention, belongs to the driving mechanism field, discloses a driving mechanism with the free load unloading function. The driving mechanism comprises a housing, a motor fixed at the outer side of the housing, and a transmission gear set. A motor output end penetrates the housing and is fixedly connected with the transmission gear set. A driving gear shaft is connected inside the housing by abearing in a rotating manner; a driving gear engaged with the transmission gear set is fixedly connected to the outer side of the driving gear shaft; and an output screw that can not rotate relatively is arranged at the inner side of the driving gear shaft in a sliding connection manner. Compared with the prior art, the driving mechanism has the following beneficial effects: the structure is simple; the mechanism is used conveniently; the axial relative movement is realized while the output shaft rotates and thus load unloading is realized while no motor or connecting sleeve is loaded; and the driving mechanism is worth promoting.