Aiming at the path planning problem of aerial vehicles with unexpected threats a virus-evolutionary particle swarm optimization algorithm (VEPSO) is proposed based on basic particle swarm algorithm.Combined with the theory of the biological virus-evolutionary system a biological virus mechanism is introduced in the basic particle swarm and two kinds of infection-based operation reverse substitution and incorporation operation are executed.The horizontal infection and vertical propagation of virus are used to maintain the individual diversity of the particles in path planning thus the local search capability of the algorithm is enhanced and the problems of local optimum and the slow convergence speed are solved.Simulation results show that the VEPSO algorithm is faster and more effective under the same path constraints.