The invention provides an intelligent decision-making method and a device for unmanned aerial vehicle task allocation under vehicle-machine cooperation. The method comprises the steps that a heterogeneous task set and road network data are acquired; constructing a path planning model; calculating the shortest path when the vehicle independently completes all tasks in the heterogeneous task set; and according to the shortest path, the preset constraint condition and a preset heuristic allocation algorithm, determining the shortest path. Determining whether each task in the heterogeneous task set is allocated to the unmanned aerial vehicle one by one; and obtaining respective tasks executed by the unmanned aerial vehicle and the vehicle when the optimization target is realized, and outputting respective optimal paths of the vehicle and the unmanned aerial vehicle when the vehicle and the unmanned aerial vehicle jointly complete all tasks in the heterogeneous task set. According to the method, a two-stage solving algorithm is adopted for calculation, and the optimal path can be obtained more easily.