Abstract: The rotational speed of the hydrodynamic shaft is the key factor affecting the performance of the hydrodynamic rotary spray dust suppression device. In order to increase the rotational speed of the hydrodynamic shaft to improve the dust suppression effect of the device, the relationship between the rotational speed of the hydrodynamic shaft and the water supply pressure, the spray amount and the internal flow field structure was studied, and the mathematical model of the correlation between the spray amount and the hydrodynamic shaft speed was obtained. The results show that the speed of hydrodynamic shaft increases with the increase of water supply pressure, but the increase rate becomes smaller. The increase rate at water pressure of 3 MPa is 35.8% of that at water pressure of 0.6 MPa. When the water supply pressure is less than 3 MPa, the speed can be directly increased by increasing the water pressure. When the water supply pressure is higher than 3 MPa, the water pressure has little effect on the speed of the hydrodynamic shaft, and the speed can be increased by improving the flow field structure of the hydrodynamic shaft to reduce local resistance.