Abstract: The complex surface building method of the existing screw-sleeve pair goes against the moulding process. According to the problem, a surface building method of the pair based on circular cross section and cylindrical helix was investigated, the surface equation of cone screw and sleeve was established based on the space meshing theory. The contact characteristics and the sealing mechanism of the pair were systemmatically studied. The theory without axial motion during the movement of the screw-sleeve pair was verified by motion simulation. Analysis show that the new surface building method makes the mathematical modeling easier, which is favorable to numerical calculation and moulding process. With good contact characteristics and sealing performance, the screw-sleeve pair built by this method will meet the working condition of the cavity type seawater hydraulic pump.