Abstract: The Rayleigh hydrodynamic-instability theory is applied to determine the frequency range of jet oscillation waves in the liquid-droplet generator. The charged capacity of each liquid droplet and the intensity of electric deviation field are derived by analyzing the charge and deviation process. The quantitative relationship between the oscillation-wave frequency for the optimum deviation and the initial jet velocity as well as the width of the charged ring is determined. Under the conditions of the different pressure, 0.02, 0.03, 0.04, 0.05, and 0.06 MPa, for feeding materials, the initial velocity of the jet with the diameter of 0.10, 0.11, and 0.15 mm is measured, respectively.