Collecting data in the near-field area of the radar using the spotlight mode based on the linear array platform, and the three-dimensional imaging algorithm of the target within the beam irradiation range is studied. The difficulty of near-field 3D imaging lies in the large amount of radar echo data, so it has high requirements on the efficiency of imaging algorithms. The application of traditional 3D back-projection algorithm is general, but the algorithm efficiency is low. Therefore, an imaging algorithm for 3D reconstruction of echo data based on the compressed sensing is proposed, Therefore, an imaging algorithm for 3D reconstruction of echo data based on the principle of compressed sensing is proposed, and it improves the elevation resolution compared with the traditional algorithm. The simulation results show that the proposed algorithm is feasible and effective, and it takes a short time to achieve 3D imaging of the target in the scene.