Abstract: A new frequency estimation method based on the digital frequency measurement structure of multi-path delay and high resolution spectrum evaluation MUSIC algorithm is proposed,which can estimate signal frequency effectively.But the frequency estimation performance in low SNR will decrease.This paper gives a modified MUSIC(MMUSIC) algorithm,which can get a new covariance matrix by reconstructing the received data and their conjugatings.This method can change the eigenvalue distributions of the covariance matrix and make it have averaged significance,thus it improves the performances of the signal frequency estimation.With the same SNR and snapshot number,the performances of the MMUSIC algorithm has better frequency estimation accuracy than the traditional MUSIC algorithm.Simulation results show that it has better feasibility and robustness,as well as the computational complexity will not increase obviously.