Abstract: In medical ultrasound imaging， amplitude and phase estimation (APES) beamforming algorithm makes the amplitude estimation of the desired signal more robustly， but it is at the expense of resolution. To solve this problem， the adaptive beamforming algorithm was proposed which was based on APES and was combined with subspace projection. Firstly， the weighted vector was calculated by the amplitude phase estimation algorithm， and then the weighted vector was projected to the desired signal subspace of the echo signal to suppress the noise and interference， and to improve the resolution and contrast of the image. The simulation results show that the proposed algorithm is superior to the original amplitude and phase estimation algorithm in terms of resolution， contrast and robustness.

Key words: subspace, projection, amplitude and phase estimation, beamforming, ultrasound imaging