The invention provides a compensator for a water injection pipe. The compensator for the water injection pipe comprises a retreat stopping part, a locking part and a control part, wherein the retreat stopping part comprises a retreat stopping ring and a thrusting cover; the locking part comprises a locking pipe core, a locking pipe, a locking coupling and a locking pawl spring; the control part comprises a locking pipe dowel and a shearing-off dowel; the inner side and the outer side of the lower end of an upper joint are respectively connected with the pipe locking core and the thrusting cover, the thrusting cover is fixedly connected with the locking pipe, and the locking pipe core and the locking pipe are respectively connected with the inner side and the outer side of the locking coupling; the locking pipe compacts the locking pawl spring onto the locking coupling, the bottom of the locking coupling is fixedly connected with a center pipe, the center pipe can be in externally sliding cover with a suspension short joint, and the bottom end of the center pipe is fixedly provided with an inclination guiding joint; and the upper end of the suspension short joint is fixedly connected with the locking pawl spring, the lower end of the suspension short joint is fixedly connected with an outer pipe, and the bottom of the outer pipe is connected with a lower joint.