The invention discloses a dry stirring mill and an operation method thereof. The dry stirring mill comprises a grinding cylinder, a feeding opening, a discharging opening, a mill air inlet, a mill air outlet, a main shaft, a driving device, stirrers, a separating device and a grading air supply device; the grinding cylinder is horizontally arranged, one end of the grinding cylinder is provided with the feeding opening and the mill air inlet, and the other end of the grinding cylinder is provided with the discharging opening and the mill air outlet; the interior of the grinding cylinder is divided into a grinding area and a grinding grading area, and the grinding area is close to one side of the feeding opening; the main shaft is located in the grinding cylinder and penetrates through the center of the grinding cylinder, one end of the main shaft is connected with the driving device, and the other end of the main shaft is supported by a bearing installed on a foundation and a support; stirrers are arranged at the position, in the grinding area, of the main shaft, and the other stirrers and the separating device are arranged at the position, in the grinding grading area, of the main shaft; a trepanning area is arranged at the bottom of the portion, in the grinding grading area, of the grinding cylinder; and the position, in the trepanning area, of the grinding cylinder is connected with the grading air supply device. Grinding efficiency is greatly improved, timely separation of materials from grinding media is guaranteed, and reliability and stability of the mill are improved.