Abstract: Based on the conventional algorithm,the maximum likelihood DOA estimation of the MIMO radar is presented according to the principles and echo model of the MIMO radar.Subsequently the estimation consistency is proved,and the estimation variance is derived theoretically.Theoretical analysis shows that the variance of the MIMO radar is lower than that of the conventional phased array radar,and the estimation performance of the MIMO radar is better than that of the phased array radar.By means of Monte Carlo simulations,the estimation variance on different SNR,snapshots and receiving array elements are simulated,the results are consistent with the theoretical analysis.