Hydraulic pressurizer suitable for slim hole

The invention discloses a hydraulic pressurizer suitable for a slim hole. The hydraulic pressurizer comprises an upper connector, a central pipe, an outer pipe, a lower connector piston, a piston pressurizing rod and a spring, wherein the top of the outer pipe is connected with the top of the central pipe in a sealed mode; the central pipe is enclosed in the middle of the outer pipe, and a gap cavity is formed between the middle of the outer pipe and the central pipe; a plurality of pressure relief holes which penetrate through the pipe wall of the central pipe left and right and communicate with the gap cavity are formed in the central pipe; and the bottom of the outer pipe is connected to the outer portion of the lower connector piston in a sleeving mode. The hydraulic pressurizer suitable for the slim hole is simple in design, safe and reliable, and the efficiency of converting high-pressure drilling fluid power into axial thrust is higher; and through ordered arrangement of the pressure relief holes and c