To solve the problems of small scale, possible occurrence of repeated reconnaissance and low reconnaissance efficiency without considering energy constraints, a multi-target trajectory planning algorithm based on energy constraints for UAV swarm cooperative reconnaissance is proposed.Firstly, various energies required by UAV missions are modeled, and the consumption of flight energy, hovering energy and data transmission energy is quantitatively analyzed.Then, the idea of graph theory is used to model the reconnaissance region and the reconnaissance target of the swarm, a new trajectory planning algorithm model is built under the energy constraints, and the collaborative optimization of the UAV swarms trajectory is conducted to reduce the overall energy consumption of the swarm.The simulation results show that the proposed algorithm is significantly better than the representative distance-based trajectory algorithm in terms of energy consumption and reconnaissance time.When 10 UAVs scout 100 targets, the energy consumption is reduced by 48%, and the reconnaissance efficiency is higher and the convergence speed is faster.