Large-diameter check valve, also known as counterflow valve, can be applied to various medium pipelines according to different materials. The large-diameter check valve installed on the pipeline becomes one of the fluid components of the complete pipeline. The opening and closing process of the valve disc will be affected by the transient flow state of the system in which it is located; In turn, the closing characteristics of the valve disc have a negative effect on the fluid flow state. The working characteristics of large-caliber check valve are large load variation, small opening and closing frequency, long service life once put into closed or open state, and no movement of moving parts is required. However, once there is a "switching" requirement, it must be flexible, which is more demanding than the common mechanical movement. Because the large-diameter check valve is qualitatively determined to be used for fast closing in most practical applications, the medium is in reverse flow at the moment when the large-diameter check valve is closed. With the closing of the valve disc, the maximum backflow speed of the medium rapidly decreases to zero, and the pressure rises rapidly, which may produce a "water hammer" phenomenon that may damage the pipeline system.