The invention discloses a novel double-acting hydraulic hammer. The novel double-acting hydraulic hammer specifically comprises a shell 1 and a hammer core 2; an impact plunger 4 is arranged between the shell 1 and the hammer core 2; a positioning ring 3 is arranged between the top of the inner wall of the shell 1 and the top of the impact plunger 4; the impact plunger 4 is connected with the hammer core 2, and adopts a seal consisting of a slide ring and a star-shaped ring; a power device 5 is arranged between the shell 1 and the hammer core 2; a speed reducing mechanism of the shell 1 is connected with a power conversion mechanism 6; and an overflow valve 7 is additionally arranged between the top of the inner wall of the shell 1 and the top of the impact plunger 4. The novel hydraulic hammer is simple in structure, convenient for use, not liable to deform and incapable of generating the liquid leaking and valve blocking phenomenon, the service life is prolonged, the use performance is improved, and the novel hydraulic hammer is stable, reliable and convenient for maintenance and disassembly.