A cotton chemical topping system based on top bud intelligent recognition was designed to achieve precise operation, rational and efficient use of cotton chemical topping agents, and reduce environmental pollution caused by excessive use of chemical topping agents. The system mainly consisted of cotton top bud recognition system, control system, and spraying system. A cotton top bud recognition model was constructed by using the YOLO v5s algorithm. The control system adopted STM32F407 microcontroller, which was responsible for receiving signals from the recognition system and controlling various cotton topping agent pipelines. At the same time, the display interface can display real-time parameters such as the driving speed of the equipment, the flow rate of the medicine, and the liquid level of the topping agent. The experimental results showed that in the field all day light experiment, the morning and afternoon time periods had the best recognition performance. At a speed of 0.4m/s, the average recognition rate was about 94%. When the signal transmission interval was 100mm, the success rate of successfully sending signals to the lower computer reached 92%. The field target spraying experiment showed that the effective spraying rate was 94%, which met the spraying requirements.