Taking the incoherent signal source as the research object,this paper comprehensively analyzes the performance of Direction of Arrival (DOA) estimation of the monostatic coprime array MIMO radar.Firstly,the direction finding signal model of monostatic MIMO radar based on sum coarray and sum-difference coarray is derived on the basis of summarizing the structural characteristics of the coprime array.Then,by using the Multiple Signal Classification (MUSIC) algorithm,the DOA estimation methods of monostatic MIMO radar based on sum coarray and sum-difference coarray are introduced in detail respectively.Finally,through simulation experiments,a comparison with the uniform linear array MIMO radar with the same number of elements is conducted,which verifies the superiority of the DOA estimation performance of the coprime array MIMO radar.