An anchor rod includes a sleeve open at one end and having a blocking plate at the other end; a pressure relief pipe fixedly arranged on an inner wall of the sleeve; and a rod body. A guide hole is formed in a center of the blocking plate. A part of the rod body penetrates through the guide hole and extends into the sleeve. A gap is formed between the pressure relief pipe and the blocking plate. An overflow valve is connected to the pressure relief pipe. A piston in sliding seal fit with the sleeve and the pressure relief pipe is arranged at the rod body. A sealing ring in sliding seal fit with the rod body is arranged at the inner wall of the guide hole; and a sealing cavity between the blocking plate and the piston in the sleeve is filled with emulsion.