Aiming at the phenomenon of dust diffusion in the process of grab unloading, the comprehensive dust suppression system of dust isolation and negative pressure suction around the air curtain is studied by combining the air curtain dust isolation and negative pressure suction technology. By using CFD-DEM two-way coupling simulation method, the dust isolation performance of the air curtain around is simulated, and it is concluded that the air curtain jet speed of 8m/s can effectively block dust. At the same time, based on the theory of negative pressure suction, the calculation formula of the change of the mass flow rate of suction air with the unloading time is derived by CFD fluid mechanics method, and the simulation and experimental model of grab unloading is established. The distribution map of the discharge plane flow field and the mass flow rate of the hopper mouth are extracted by simulation to reflect the movement of the dusty air flow in the hopper. Through experiments, the variation law of the discharge dust movement and the dust suppression effect are compared before and after the installation of air curtain and negative pressure suction device. The conclusions are as follows: the maximum dust concentration at the hopper mouth is reduced by 738.4mg/m3, the concentration value is reduced by about 95.3%, and the time for dust to completely settle is reduced by 60%, which provides a guiding significance for effectively solving the spread of discharging dust.