Voronoi graph method is used for forest-fire relief supplies’ shortest way of planning. Global path planning model has been established initially based on Voronoi and Geography Information System (GIS) method. Ellipse model is used to express forest fire spread region. For simplified computation, the excircle of the ellipse instead is utilized to calculate threat degree, which also makes the planned route has bigger security. In order to enhance flight vehicle’s feasibility, smooth processing carries on above path’s elevation by grade limitation smooth algorithm and curvature limit smooth algorithm. The simulation result shows: this simple plan method might effectively solve the problem of vehicle’s 3D global path planning, simultaneously also lay the foundation for the actual flight in dynamic flight path planning.