The 300X slow shut-off check valve is an intelligent valve intended for installation in the pump outlet of a high-rise buildings' water supply system. When uses it effectively prevents the reverse flow of a medium, as well as water hammer-type phenomena. This valve utilizes a motorized valve, check valve and water hammer eliminator at the same time and can effectively increase the safety and reliability of a water supply system. It integrates such functions as slow opening, fast and slow closing in order to eliminate water hammer, so as to prevent the occurrence of pump-on water hammer and pump-off water hammer. The valve can automatically realize turning on/off according to the operation specification of the pump. By pressing the On/Off button of the pump motor; a large flow and small pressure loss can be achieved. Our slow shut-off check valve are suitable for use with pipes of 600 caliber and below.