Abstract: A fast and effective method of radome boresight error (BSE) optimization by adjusting the phase compensation value of phased array elements is proposed. Particle swarm optimization (PSO) is adopted, applying to the case of continuously adjustable phase or digital discrete phase. With the phase offset optimization technology in the optimization encoding, the quantization error of low phase shifters is effectively reduced. The speed updating formula of BSE optimization is improved combined with prior information, and the convergence speed is improved. Pre-computed matrices on behalf of field source relationship are established to reduce the computation of solving the fitness function and save the numerical calculation time. The validity and effectiveness of the presented approach are confirmed by optimal design of a 16 elements array-radome system with 4-bits phase shifters.