Adjustable slow-closure check valve

The utility model provides an adjustable slow-closure check valve which comprises a valve body, a valve seat, a valve clack, a spring, a slow-closure cylinder, an adjustable piston, a valve element and a valve rod. The valve seat is arranged in the valve body, the valve element is fixed on the valve body, a threaded hole is formed in the center of the closed end, and a damping groove is formed in the circumference of the adjustable piston; one end of the valve rod is sleeved with the opening end of the adjustable piston; the other end of the valve rod is fixedly connected with the valve clack; the slow-closure cylinder is fixedly installed in the valve element and the middle of the valve rod penetrates through the slow-closure cylinder; a piston cavity matched with the adjustable piston is formed in the slow-closure cylinder; the valve rod is sleeved with the spring and the spring is located between the valve clack and the slow-closure cylinder. When media in the adjustable slow-closure check valve flow back,