The invention relates to an airtight pulp dispersing device. The device comprises a motor, a dispersing revolving shaft, a dispersing head which is connected with the lower end part of the dispersing revolving shaft, a discharging container and a dispersing container, wherein the motor is connected with the discharging container by a connecting piece; a cavity is formed between the connecting piece and the motor; the connecting piece is provided with a high-pressure air inlet which is communicated with the cavity; high-pressure air enters the cavity to form a high-pressure air area; the connecting part of the dispersing revolving shaft and the connecting piece is provided with an annular air gap for the high-pressure air to pass through; and the high-pressure air which enters the cavity forms a sealed air curtain at the annular air gap so as to prevent corrosive substances or other harmful substances which enter the discharging container from escaping. The airtight type pulp-dispersing device seals easily-leaking parts between the revolving part and the container or other static parts in an airtight mode, thereby reducing the leakage of the corrosive substances or the other harmful substances which are contained in materials to the greatest extent during the production of the device and particularly under the condition of the high-speed rotation of the revolving shaft.