Abstract: The variable application technology aims to improve the utilization rate of pesticides, reduce agricultural costs, appropriately reduce the amount of pesticides, reduce pesticide residues, and reduce environmental pollution. It is an important topic in precision agriculture and the development direction of pesticide application technology. This paper summarizes the field information collection method, the variable application control method, and the variable application control algorithm in the key technology of variable application. Firstly, the field information acquisition technology based on geographic information technology and real-time sensor technology is explained. The second analysis includes variable pressure regulation, chemical concentration regulation, and pulse width modulation variable application control methods and analyzes the advantages and disadvantages of each control method. Pulse width modulation has broad application prospects because of its better dynamic response characteristics and flow regulation performance. Finally, the most important variable application control algorithms（fuzzy control algorithm, PID control algorithm, and BP neural network） are summarized and researched. It is understood that the combination and improvement of different algorithms improve the variable application control performance. Aiming at the problems of domestic variable application technology, suggestions are made to provide a certain reference for the development and promotion of variable application technology in my country.