The previous research on variable rate sprayer was presented. Experimental scheme was designed by using photoelectric equipment, which measured droplet travel time with four types of nozzles at different forward speeds and different pressures. Result showed that droplets reached the target ahead of the time when the boom passing over it due to the spraying angle. Meanwhile, the time ahead could be the necessary compensation of the system response time on variable rate sprayer. The orthogonal experiment and F-test showed that nozzle type had more significant impact on droplet travel time, and the forward speed of sprayer had significant impact on droplet travel time on 5% significance level. Fluorescence tracer and luminescence spectrophotometer were utilized in analyzing droplet deposit distribution on moving paper belt at different moments，which showed hollow core nozzle hold great potential of drifting on boom sprayer.