Abstract: In order to explore the influence of many factors on charge-mass ratio in electrostatic spraying process, the charge-mass ratio of four orifice nozzles was tested by induction charge method. A nozzle with significant change of charge-mass ratio was selected, and then the charge voltage, spray pressure and conductivity of liquid medicine were improved by single factor test method. The influence of various factors on charge mass ratio was discussed. On this basis, the Box-Behnken design-response surface method was used to optimize the three-factor and three-level optimization tests of the charging voltage, spray pressure and chemical conductivity of the TXVK-3 nozzle.The results showed that when the voltage was 6.9 kV, the spray pressure was 0.3 MPa, and the conductivity was 13.9 mS/cm, the average charge-to-mass ratio was -0.227 mC/kg, and the relative error was less than 2%.