Abstract: Abstract: Research in the air-assisted spraying field has been focusing on optimization of structure, droplets deposition, droplets drift and recovery. But the droplets transfer in wind field is not clear yet. In this study, we investigated the variation of droplet parameter especially diameter in wind field for long-range air-assisted sprayer. The droplets parameters of long-range air-assisted sprayer was measured and calculated and analyzed after the droplets were ejected from the nozzles by using a prototype and laser particle size analyzer. The testing prototype had the horizontal spraying range of 13 m and spraying width 2.29 m. During the test, the sprayer sprayed water instead of pesticides liquid under the plunger pump pressure of 1.8 MPa. The experiments of droplets parameters included 3 situations: 1) the droplets were sprayed from the nozzles without air blowing; 2) the droplets were sprayed within the width under the condition of the long-range air-assisted sprayer; and 3) the droplets were sprayed within the range under the condition of the long-range air-assisted sprayer. In the test of spraying within the width, droplets were sampled in 7 different heights at 7, 8 and 9 m away from the nozzles. In the test of spraying within the range, droplets sampling points were arranged along with the sprayer duct axis, starting with 1 m away from the nozzles position and separated from each other by 0.5 m. The results showed that there was only 1 peak in the droplets spectrum distribution and the droplets diffusion ratio was relatively small when the long-range air-assisted sprayer did not blow. The diffusion ratio was 0.70 with wind, higher than 0.61 without blowing condition. The diffusion ratio with wind was higher than 0.67, indicating that the spraying effect and droplet quality were better under the condition with wind than that without blowing. Within the spraying width, the droplets volume median diameter became large along the direction from top to bottom of the droplets column, or the lower droplets were larger than the upper in the same vertical plane of the droplets column. In the last 2 situations with wind, the droplets volume median diameters were all larger than 50 μm and the volume cumulative percentage of large droplets diameter larger than 400 μm was lower than 0.4%. In addition, two peaks were found in the droplets spectrum, which was different from the 1 peak in the situation without blowing. The wind speed was higher than 18.7 m/s within 1-2 m away from the nozzle, 6.8-13.3 m/s in 2-8 m away from the nozzle, and not less than 6 m/s in 8-10 m away from the nozzle, respectively. In general, the moving and forward transmission of droplets in wind was mainly divided into the following 3 stages: 1) within 1-2 m distance near the nozzles position, high speed air flow broke the droplets twice and thus made the droplets smaller; 2) In the middle of the range, the droplets diameter became larger due to collision and aggregation with the moving and transmission under the medium speed air flow; 3) In the end of the range, the droplets diameter decreased because of the evaporation and diffusion in the low speed flow. The study provides information for sprayer design and optimization.