Abstract: The optimization formula of vibration frequency was found based on the jet theory in this study. It was applied to UO₂ fuel microsphere production, and the calculated optimum vibration frequency well agrees on the experimental value. The effects of air density, the solution’s viscosity, the surface tension and density on optimum vibration frequency were analyzed. Air density’s effect is very little, however, optimum vibration frequency decreases with the solution’s viscosity increasing, and increases with the solution’s surface tension and the solution’s density increasing.