Ultralow-temperature axial-flow type check valve

The ultralow-temperature axial-flow type check valve comprises a valve body, a valve seat, a valve element and a valve shaft, a pressure plate is arranged in a medium inlet, the valve shaft is sleeved with a spring, a supporting seat is arranged at the left end of the spring, a cylinder is fixedly arranged at the right end of the supporting seat, the cylinder is sleeved with the left end of the spring, and the valve element is pushed by the spring to move rightwards; sealing is formed between the sealing surface of the valve core and the valve seat; the supporting seat is fixedly connected with the valve body, an axial guide hole is formed in a cylinder of the supporting seat, the left end of the valve shaft is inserted into the axial guide hole, a buffer disc is arranged at the left end of the supporting seat, a buffer cavity is formed between the buffer disc and the supporting seat, and the buffer disc is connected with the left end of the valve shaft; a valve body support is fixedly arranged in the valve b