The dispersion model is a very important issue in UAV swarm technology.In the research of dispersion model of UAVs,the most important effort should be exerted on building the motion equations for each UAV.Based on modeling the 2D centroid motion equations for the UAVs,virtual constant gravitation,boundary force and Lennard-Jones molecular force are designed to simulate the forces acted on the UAVs in dispersion,which aims to satisfy the requirements of alignment and obstacle avoidance.The simulation results obtained from numerical outcome of motion equations showed that,the dispersion model helps the swarm numbers to maintain a safe distance from each other and ensures that they can fly in a rough uniform direction.