When the gate valve is closed, the sealing surface can only rely on the medium pressure for sealing, that is, only rely on the medium pressure to compress the sealing surface of the gate to the other side of the valve seat to ensure the sealing surface seal, which is self-sealing. Most of the gate valves are forced to seal, that is, when the valve is closed, relying on external force to compress the gate to the valve seat for ensuring the sealing performance of sealing surface. The valve body is precision casted, and the precise geometrical dimensions make the interior of the valve body do not need any finishing to ensure the sealing of the valve.