The invention discloses a sorting machine integrating gravity, magnetic and buoyancy fields and a sorting method of the sorting machine. The sorting machine comprises a machine body, the machine body is of a columnar structure, a feeding pipe is connected with the middle of the machine body in the radial direction, the feeding pipe is connected with a pulp distributor in the machine body, a first hollow coil is arranged at the position, below the feeding pie, on the outer portion of the machine body, the lower edge of the machine body is connected with a sorting grading cone, a flushing water pipe is arranged on the sorting grading cone, a second hollow coil is coaxially arranged on the outer portion of the sorting grading cone, the upper edge of the machine body is connected with a tailings groove, a third hollow coil is arranged at the connecting position of the machine body and the tailings groove, the three hollow coils can be vertically adjusted along the axis of the machine body, a concentrate discharging opening is formed in the bottom of the sorting grading cone, and a tailings discharging opening is formed in the end of the tailings groove in the top. The multi-force-field sorting machine is integrated with multiple sorting methods of gravity sorting, buoyancy sorting and magnetic sorting, and is integral, the magnetite concentrate grade is improved, the recovery rate is ensured, the magnetite reverse flotation flow sheet is effectively shortened, and the sorting machine and method are suitable for the reverse flotation iron extracting and silicon reduction process of magnetite.