The invention discloses a high-tightness liquid hydrogen pump. A pump body is fixedly connected to the upper end of a base through a fixed nut; the upper end of the pump body is fixedly connected witha liquid inlet; a liquid outlet is fixedly connected to the left end of the pump body; the end parts of the liquid inlet and the liquid outlet are in threaded connection with connecting pieces; thread grooves are formed in two sides of the connecting pieces; sealing washers are arranged at the inner ends of the thread grooves; clamping blocks are arranged at two side ends of the connecting pieces; limiting blocks are arranged at the side ends of the liquid inlet and the liquid outlet; electromagnetic valves are fixedly connected to the side walls of the liquid inlet and the liquid outlet; theliquid outlet and the liquid inlet are in threaded connection by using the connecting pieces; through the internal sealing washers and the limiting blocks on the outer sides, the connecting places are tightly sealed, so that the sealing of the connecting places is reinforced, such natural disasters as fire caused by hydrogen leakage are prevented, and the use safety of equipment is improved; andthe high-tightness liquid hydrogen pump is reasonable in design, simple in structure and suitable for popularization and wide application.