The invention provides a rotary main shaft device for a micro electric spark machining machine which is applied to the technical field of micro machine manufacturing of micro machining limitation. The rotary main shaft device for the micro electric spark machining machine comprises a rotary main shaft, precision bearings, an electrifying device, an electric brush, insulating plastic, an upper end cover, a first insulating body, a ceramic material, a second insulating body, an inner insulating pipe, an outer liquid passing pipe sleeve, a motor, a synchronous belt, a main shaft shell, a lower end cover and bolts. The motor is arranged on a stand of the main shaft shell. One end of the synchronous belt is connected with an output shaft of the motor in a sleeved mode, and the other end is connected with a belt pulley of the rotary main shaft in a sleeved mode. The second insulating body is arranged on the upper end cover. The inner insulating pipe is arranged inside the second insulating body. The outer liquid passing pipe sleeve is arranged on the upper portion of the second insulating body and the external of the inner insulating pipe. A micro hole, a groove and a curved face with the diameters lower than 0.1 mm can be machined on quenched steel hard alloy, stainless steel and other super-hard and super-soft conductive materials, a high-frequency supersonic vibration technology is adopted by the rotary main shaft, the production efficiency is improved, the production cost and the electrode loss are lowered, and the machining quality is improved.