Abstract: The optimal strategy problem of multi-frame range gate pull-off (RGPO)jamming with unknown environment model was studied. We used improved Particle Swarm Optimization (IPSO) to solve the problem. First, we used the difference between the center of the range gate and the true target position as the evaluation index of the jamming effect, and constructed a multi-frame joint optimization model of RGPO jamming. Then, in order to solve the difficulty of obtaining objective function analytical expressions, a fitting method of Monte Carlo objective function combined with reward mechanism was proposed. On this basis, a strategy optimization method based on particle swarm optimization algorithm was proposed for the difficulty of high optimization dimension. Finally, numerical results were provided to verify the validity of the proposed algorithm.