Abstract: An improved pattern synthesis algorithm for antenna array named hybrid adaptive genetic particle swarm optimization (HAGPSO) is described, which aims at reducing the difference between the synthesized pattern and the actual pattern. HAGPSO algorithm based on genetic algorithm and particle swarm optimization takes into account not only the actual element pattern, the array mutual coupling and electromagnetic environment effects, but also adds adaptive factor to accelerate convergence. Thus the synthesized pattern is consistent with the simulated pattern. Beamforming for LTE basestation antenna as an engineering example is used to prove the correctness and effectiveness of the HAGPSO.