Abstract: In order to optimize the design of plant protection equipment, an H-type combined sprinkler was studied, and the influence of field operation parameters of this combined sprinkler on the application effect was studied. The structure and working principle of the H-type combined sprinkler are described and analyzed, and the optimal parameters of each component of the combined sprinkler are obtained according to field tests. The test shows that under the pressure of 0.3-0.9 MPa, the flow rate of the H-type combined nozzle is 208.3-293.3 mL/min, the droplet size distribution span is 0.71-0.82; the flow rate of the conventional nozzle is 724.2-1427.2 mL/min, the droplet particles the diameter distribution span is 1.56-1.71.At 1.5-0.3 m, the droplet deposition volume of the H-type combined nozzle is 0.129-4.256μL/cm~2, and the coverage rate is 21.3%-55.6%; the droplet deposition volume of the conventional nozzle is 0.062-3.462μL/cm~2, coverage rate is 18.6%-49.2%. In the case of conventional spraying, compared with conventional spray nozzles, the H-type combined spray nozzles have increased 5.29%, 6.56%, 6.17% and 4.86% in the control of tomato gray mold, cucumber powdery mildew, grape thrips and cowpea aphids; The spraying effect of H-type combined spray nozzle-1/2 water volume+2/3 dose is basically the same as that of conventional spray nozzle-conventional water volume+conventional dose.The H-type combined sprinkler has stable performance during operation, and its application effect on crop diseases and insects is better than that of conventional sprinklers. It can effectively improve the utilization rate of pesticides. The coverage rate is ideal. The spraying of the chemical liquid is uniform. Various indicators meet the actual production needs of crop spray.