A variable pitch spiral compression machine head mainly comprises a dynamic spiral rotor with multistage vanes, multistage axial static diffuser rings and a static compression cover. By means of the method that the spiral ascent angle and the pitch of a spiral compression vane are adjusted stage by stage, the distance between adjacent spiral vanes and the passage section area are changed. By means of the multistage compression method that the spiral vanes rotating at a high speed press in a centrifugal mode stage by stage and the method that the multistage diffuser rings are arranged axially and diffuse pressure axially, the process that gas is pressed in a centrifugal mode and pressurized stage by stage is achieved. A high pressure ratio can be generated, high pressure can be borne, the diameter of a cylinder of a compressor is reduced, and miniaturization of the compressor is facilitated. The number of the spiral vanes of the compressor, the diameter of a base circle, the number of compression stages, the pitch of the spiral vanes and other important design parameters can be determined according to compressible performance of actual gas and the pressure ratio of the gas, and the compressor can be designed flexibly. By means of the long cylindrical compression machine head, the heat conductive area of the cylinder is increased, the compression process is close to the constant-temperature compression process, and compression work is reduced.