The invention provides a magnetorheological pilot-operated overflow valve belonging to the technical field of hydraulic drive. The magnetorheological pilot-operated overflow valve comprises an end cover, an end cover seal ring, a magnetorheological valve housing, a coil, an iron core, a valve core, a pilot-operated valve body, a pilot-operated seal ring, a damp piece, a main valve housing seal ring, a spring, a guide rod seal ring, a guide rod, a main valve housing, a main valve core, a main valve seat insert, a main valve seat, a main valve body and a damper. The main valve core is in a parabolic ball shape, and the half cone angle of the valve core is larger than that of the valve seat, thus, the pressure difference between an inlet and an outlet of a cone valve can be effectively reduced; the minimum negative pressure moves backwards along a liquid flow direction, appears at the back of the valve core and is avoided appearing in the valve seat, thus, the possibility of gas etching is reduced, noise is reduced, key parts of the valve core and the valve seat are protected, and the service life of the magnetorheological pilot-operated overflow valve is prolonged.