The spray deposition uniformity is an important measure index to evaluate spray quality. Through improving the spray deposition uniformity, the pesticides can be saved under the premise of high pesticide effect. Aiming at studying the uniformity characteristics of dynamic spray deposition for PWM variable spray system, the carmine solution was used as spray reagent and matrix tray with holes was put on the conveyor to collect droplets, and then the spray deposition concentrations of each hole were calculated by the method of concentration-absorbance measurement. The impacts of spray pressure, frequency and duty cycle of PWM signal on spray deposition uniformity for single nozzle were tested from three aspects of whole area, forward moving and spray bar direction. The research results suggested that for single nozzle, the frequency of PWM signal had bigger impact on spray deposition uniformity in forward moving direction than that in spray bar direction and there was no need to set too large value of frequency unless it was required to guarantee the continuity of spray. Moreover, before the duty cycle of PWM signal reached a certain value that the flow rate of spray became stable, the duty cycle only influenced the spray deposition uniformity in forward moving direction significantly for single nozzle, and when the duty cycle was bigger than the value, it can influence the spray deposition uniformity in both the forward moving and spray bar directions for single nozzle. The results also indicated that the spray pressure had opposite effect on spray deposition uniformity in forward moving and spray bar directions for single nozzle. These results could provide references for setting operating parameters of spray work and studying the uniformity characteristics of dynamic spray deposition for multi nozzles.