One-way valve and mud valve device capable of automatically adjusting size of valve port

Provided is a one-way valve. The one-way valve comprises a valve cover rotating shaft, a one-way valve cover, a floating ball rotating shaft, a valve cover floating ball, a valve cover latch hook, a lock shaft and a one-way valve body which cooperate with one another, wherein the one-way valve body is connected to the lower end of a water tank body, the one-way valve cover is connected with the one-way valve body through the valve cover rotating shaft, the one-way valve cover rotates freely around the valve cover rotating shaft, the valve cover latch hook is fixedly connected with the valve cover floating ball integrally and is connected with the one-way valve cover through the floating ball rotating shaft, the lock shaft is fixedly connected on the one-way valve body, and the valve coverfloating ball assists in opening and closing of the one-way valve cover under the buoyancy of water in an outlet flow velocity induction cavity. The invention further discloses a mud valve device capable of automatically adju