The dosage sprayed upon per unit area is an important indicator to measure the performance of spray. In order to ensure the consistency of the dosage sprayed upon per unit area, and realize the real-time control of the spray volume, based on the analysis of aerial variable spray technology, a set of hierarchical control algorithm of aerial variable spray for UAV was proposed. A hierarchical control table was created based on the level of each spray parameter and the opening degree of the valve. And then a corresponding opening degree value of the valve was obtained when spray parameters changed by combining hierarchical control formula. And it can calculate the spray volume to realize the purpose of automatically adjusting the spray volume. A set of real-time monitoring system of aerial variable spray for UAV was developed in view of the algorithm and multi-information fusion technology based on single chip microcomputer. And the system realized the real-time monitoring of information such as flight track, flight height, flight speed, spray volume and liquid residue through the design of software and hardware. And experimental studies of flight track monitoring, spray volume monitoring, liquid level monitoring and variable spray control were carried out. The test results showed that the system can accurately monitor a variety of spray parameters in real time and precisely regulate the spray flow according to the parameter changes. And the mean deviation of flight track monitoring was 0.98m. The mean deviation of spray volume monitoring was 3.57%. The average deviation of liquid level monitoring was 1.97%. The maximum error of spray volume control was 9.26%.