A semitrailer traction pin device is fixed on a cantilever of a tractor and comprises a traction pin, a pallet traction plate matched with the traction pin and an installation mechanism of the traction pin, wherein the installation mechanism comprises a guide rail parallel to the longitudinal direction of a vehicle frame, a sliding seat capable of sliding on the guide rail, an actuating device capable of driving the sliding seat to move along the guide rail and a locking part which can fix the sliding seat with the guide rail; the guide rail is fixed on the front vehicle frame cross beam and the back vehicle frame cross beam of the cantilever; the actuating device articulates the driving end of the actuating device with the sliding seat along the longitudinal direction of the vehicle frame, while the non-driving end of the actuating device is fixed on one of the cross beams; and the traction pin is arranged on the sliding seat. The semitrailer traction pin device ensures that a front cantilever of a semitrailer can be adjusted according to different clearance radius of a matched main machine, and can reasonably allocate the weight born by a semitrailer to the main machine and the semitrailer.