The invention discloses a mechanical vacuum liquid level control valve. The mechanical vacuum liquid level control valve comprises a fixing part, a valve body and a triggering part, wherein the fixingpart comprises a base used for fixing and installing and a guide pipe vertically arranged on the base, the valve body is arranged at the top end of the guide pipe, a working hole, a negative pressurehole and an emptying hole which communicate with one another are formed in the valve body, the working hole, the negative pressure hole and the emptying hole communicate with one another through a connecting cavity, a magnetic bead is movably arranged in the connecting cavity, the negative pressure hole is vertically formed, the emptying hole communicates with the interior of the guide pipe, thetriggering part comprises a triggering assembly and a floating assembly arranged at the bottom of the triggering assembly, the triggering assembly is movably arranged in the guiding pipe in the axialdirection of the guide pipe, the bottom end of the triggering assembly penetrates out of the base in a sliding mode, a magnetic block is arranged at the top end of the triggering assembly, and the magnetic block and the emptying hole are coaxially arranged. The mechanical vacuum liquid level control valve is simple and reasonable in structure, low in manufacturing cost, free of electricity, reliable in performance and long in service life.