Abstract: The traditional minimum variance(MV)adaptive beamforming algorithm for medical ultrasound has the disadvantages of poor robustness， limited image contrast enhancement and high algorithm complexity. So， according to the minimum variance beamforming based on QR decomposition(QRMV)， the sign coherence factor was introduced， and an adaptive beamforming algorithm of QRMV combined with sign coherence factor was proposed. The simulation results showed that the proposed algorithm in the aspects of resolution and contrast is superior to the conventional delay and sum(DAS)， MV and QRMV， and its performances are very close to SFMV， but its computational complexity is far lower than SFMV.

Key words: minimum variance(MV), sign coherence factor(SCF), QR decomposition, resolution, contrast