The invention provides an automatic traction device, and relates to the field of tractor connecting auxiliary equipment. The automatic traction device comprises a traction rod, a dragging pin, a guiding shell and a limiting pin assembly, and the guiding shell is connected with the traction rod; the dragging pin is placed in a hole of the guiding shell and penetrates through a trailer ring; the limiting pin assembly comprises a dragging pin locking shaft and a dragging pin locking spring, the dragging pin locking shaft is arranged in a transverse hole of the guiding shell, the dragging pin locking spring is arranged at the rear end of the dragging pin locking shaft, and a conical top part is arranged at the front end of the dragging pin locking shaft; a first guiding bevel angle corresponding to the conical top part is arranged at the upper side corner of the dragging pin; and a second guiding bevel angle corresponding to the conical top part is arranged at the upper side corner of the upper bifurcation of a rocker arm. According to the automatic traction device, the pull-out and reset of the limiting pins can be realized only through mechanical means.