The invention discloses an automatic overturning and pressing concave sealing plate valve mechanism. The mechanism comprises a plate valve upper joint and a valve seat and a valve plate which are arranged in the plate valve upper joint, wherein the valve seat is hermetically connected to the lower end of the plate valve upper joint, and the upper end surface of the valve seat is a radian curved surface; the valve plate is arranged above the valve seat, the whole valve plate is of a circular arc-shaped concave plate structure, and the lower end surface of the valve plate is provided with the radian curved surface which is hermetically matched with the upper end part of the valve seat; and the automatic overturning and pressing concave sealing plate valve mechanism further comprises a valveplate driving assembly which is arranged above the valve plate and is in linkage with the plate valve to open and close. According to the mechanism, the hydrostatic column pressure is used as power topull the valve plate to turn over, and a spring and hydrostatic column pressure are used to apply pressure to the valve plate so as to improve the sealing performance of the valve plate; the valve plate overturning and pressing mechanism has reliable operation and improved sealing performance and meets the coring operation condition; and the structure is simple, and the mounting and using operation is simple and convenient.