Hydraulic safety joint has the function of emergency handing-off when downhole tools are stuck. Throwing the ball, pressing and shearing the pin to achieve the loss of hand, leaving the built-in standard "GS" salvage neck after the loss, salvage using GS salvage spear. The tool can effectively transfer torque, withstand large impact force, and the drop pressure can be adjusted. It is widely used in cutting, drilling and grinding, fishing and other operations.