Abstract: The performance of hearing aids may degrade severely in noisy environment. If noise and desired sound are at different directions, a directional microphones system is able to suppress the noise in hearing aids and benefit the hearing-impaired. A low-misalignment adaptive directional algorithm based on LMS（Least Mean Square）for hearing aids is proposed in this paper. The proposed algorithm is designed for updating coefficients of the adaptive FIR so that the null of directional pattern would face the direction of noise. Compared to the available LMS, the proposed algorithm brings in a posteriori SNR and a related SNR compensation factor to update the step so that misalignment is improved in presence of desired sound. Finally, improvement of misalignment has been verified by simulation results.