Reducing check valve

The utility model discloses a variable-diameter check valve, and particularly relates to the technical field of variable-diameter check valves, the variable-diameter check valve comprises a check valve main body, a filter screen is arranged in the rear end of the check valve main body, and a connecting assembly used for being connected with a pipeline is arranged at the front end of the bottom end of the check valve main body; a cleaning assembly used for cleaning impurities is arranged at the bottom end of the check valve body. The cleaning assembly comprises a slag collecting pipe, the slag collecting pipe fixedly communicates with the bottom of the check valve body, and two movable grooves are formed in the bottom end of the slag collecting pipe. By rotating the movable plate movably connected with the fixed plate, the sealing plate can be driven to block the opening or be separated from the opening in a staggered mode, when the opening is blocked, the sealing performance of the slag collecting pipe can be