The parallel gate valve has the features of small fluid resistance, reliable sealing property, long service life, spherical pig included therein for pipeline cleaning, etc., wherein the gate plate vertically moves along the axis of the passageway to open or close the passageway. Generally, the parallel gate valves are especially applicable to the long delivery pipelines with such requirements as large scale, strict parameters and automation for petroleum, natural gas, chemical product, etc., and the flat gate valves configured with pneumatic or electric actuators, etc. can be used to realize remote operation.More