Abstract: In the prevention and control of cucumber mechanized pests and diseases, there are problems such as low utilization rate of pesticides, high labor intensity, environmental pollution and easy poisoning of operators.Based on ultrasonic atomization technology, a self-propelled cucumber ultrasonic spray application machine was designed.The design of the device mainly includes the design of the whole machine structure, the crawler chassis walking system and the ultrasonic pneumatic spray system.It is verified by the prototype performance test.The test results show that the prototype has stable walking and no obvious vibration. The application parameters are ultrasonic generator power 300 W,air pressure 50 kPa,nozzle flow 3.3 mL/min, application distance 20 cm, nozzle angle 0°,driving speed is 1 m/s, can ensure the droplet deposition and working efficiency of cucumber leaves at the same time, the coverage of the upper, middle and lower leaves is 78.63%,79.97%,72.23%, and the operating efficiency is 2.25 hm~2/h, almost No blade damage, in line with the requirements of agronomic plant protection.