Aiming at the complex nonlinear optimization problems like ground-based interceptors and space target encounter, the trajectory fast optimization design method based on IGPSO was studied. Firstly, the flight program optimum model was designed based on the characters of intercept rendezvous trajectory for launch vehicle. Then, combined the high efficiency of progressive search with randomness of particle swarm search, the IGPSO algorithm was proposed, which was applied to solve the complex nonlinear optimization problem. Finally, the IGPSO algorithm was used to simulate intercept rendezvous trajectory and the results of the simulation experiments indicated that the IGPSO algorithm could efficiently resolve the optimum design problem for the high calculation accuracy and high efficiency in optimization.