100～150 μm。Based on multi-variable quadratic regression orthogonal combined experiments, the regression equation for rotation-speed of impeller and diameter of impellers, vane number, vane fixed angle was established, and the equation for rotation-speed of impellers and spraying volume was also built. Both equations laid an important basis for impellers designing. Optimal structure parameters of impellers for the experimental sprayer have been obtained, diameter of impellers is 150 mm; six pieces of vanes; vane fixed angle is 30°. The experimental results of rotary disc nozzle with optimal structure parameters: VMD of droplets is 100～150 μm, with spraying volume changed from 0 L/min to 10 L/min under the rated rotation-speed. 