Aiming at the problems of high side lobe level, wide main lobe and high data complexity in beamforming of uniform circular array, this paper studies the beamforming method of uniform circular array. Firstly, the uniform circular array is converted into a virtual uniform linear array by using the phase mode excitation technology. On this basis, the particle swarm optimization algorithm is applied to optimize the beamforming. Finally, the equivalent array aperture is further expanded by using the linear prediction algorithm. This method not only retains the advantage of omnidirectional scanning of the circular array, but also fully utilizes the convenience of the mature algorithms of the linear array. At the same time, the resolution and freedom of the beamforming are significantly improved through aperture expansion.