A modified MUSIC algorithm based on fractional low order moments is proposed to estimate the direction of arrival of coherent signal sources in the background of impulse noise. Firstly, the fractional low-order moment matrix is calculated according to the received data of the array, so as to suppress the impact of the impact noise on the received data of the array. Then, the basic principle of modified MUSIC algorithm is adopted to solve the rank loss of array covariance matrix caused by the existence of coherent signals by conjugate rearrangement of matrices, and the estimation performance of the algorithm is improved. The effectiveness of the proposed method is verified by computer simulation experiments. Experimental results show that: The proposed algorithm can effectively suppress the impact of the impact noise and de-coherently process the coherent signal, and has higher estimation accuracy and probability of success than the fractional low-order singular value decomposition algorithm and the adaptive reconstruction method after data preprocessing.