Abstract: At present, there is redundancy in the route of helicopter spray, which leads to waste of fuel and pesticides, and serious environmental pollution and high spray cost. In order to improve the aerial spray efficiency and avoid the phenomenon of overspray, missed spray and respray in the process of aerial spray, and solve the problem of inaccurate coverage was caused, the optimal full coverage route planning method was proposed and the corresponding device was developed. Firstly, Based on the analysis of previous research on the full coverage path planning technology of aerial spray, full coverage spray route planning for R44 helicopter was studied, a set of shortest spray voyage and the most accurate full coverage route planning algorithm for aerial spray was developed. The optimal full coverage route planning method showed that the longer the spray route, the larger the spray area and the larger the pesticide consumption. Therefore, under the premise of full coverage, the shortest distance of spray route can ensure the most accurate coverage. Under the premise of without repeated spray, to ensure full coverage of the spray area, the spray route needs to be beyond the boundary of the spray area. Moreover, the excess spray area was reduced by reducing the length of spray route outside the boundary. Based on the principle of full area coverage, the spray voyage of outside the spray area was calculated and analyzed to obtain the shortest spray voyage calculation formula on the premise of full coverage, and draw the conclusion that the spray voyage was shorter when the boundary of the spraying region was parallel to the x-axis of the coordinate system. Furthermore, each boundary was taken as the x-axis to establish the coordinate system, and the shortest coordinate system of spray voyage could be obtained through the calculation formula of spray voyage. Then combined with the full coverage route planning method, the optimal full coverage routes according to different operating environments were achieved. Therefore, under the premise of full coverage of the spraying area, the spray voyage was the shortest and the coverage was the most accurate. Real-time monitoring of flight track was realized through designing of software and hardware, and information was transmitted bidirectional between plane and mobile terminal through OneNet IoT platform. Seven full coverage spray experiments with different course were carried out on three different terrain sites with different areas of rectangle, arbitrary quadrilateral and arbitrary polygon. The experiments results showed that the spray voyages of the planned course was the shortest and the redundant coverage was the least among the three test sites. The distance can be shortened by 4.920, 6.903, 59.913 km than other courses spray voyages in the three test sites; the minimum redundant coverage was 2.08%, 7.17%, and 0.57%, respectively. With the increase of spray area, the shorter the voyage was, the less redundant coverage was. And the redundant coverage of regular terrain of route planning was obviously less than that of irregular terrain. The full coverage route planning algorithm proposed in this paper can provide theoretical support for the development of aerial route planning technology and provides guidance for actual spray operations.