Lock device for controlling fluid

The invention belongs to the field of mechanical locks and particularly relates to a lock device for controlling fluid. A piston is arranged between a lock body and a lock core, wherein the lock device is fixed on an inlet and outlet passage of a fluid container, a lock body through hole matched with an inlet and outlet of the fluid container is arranged on the lock body, a lock core through holecommunicated with the lock body through hole is arranged on the lock core, the piston is movably connected on the bottom part of the lock core, and the piston has a displacement space in a certain range relative to the lock core and can be pulled by the lock core to do displacement movement. The invention has the advantages that the lock device is applicable to the fluid locking, can realize the locking effect in one flowing direction, is more disguised and is safe, reliable, convenient and practical.