Charged-spray can effectively improve the removal efficiency of fine particulate matter. The charging of spray is an important factor affecting the removal efficiency of fine particulate matter. We established a theoretical computation formula of droplet group based on the water induction charged theory to study the influences of various factors on the charge-mass ratio of droplet by changing the charged voltages

electrode gaps

atomization pressures

and annular electrode diameters

and we tested the spray characteristics. The experimental results show that the charge-mass ratio of droplet increases first then decreases as the charged voltages increase

decreases as the annular electrode diameter increases

and increases as the electrode gaps increase; the charging of spray is related to the atomization pressures

and there is an optimal atomization pressure value for each nozzle; the droplets size decreases as the charged voltage increases

the charged voltage has a weak impact on the droplet size when the droplet size is small. The experimental results have an important guiding significance in the improvement of charging performance of droplet and the application of charged-spray in control of fine particulate matter.