Abstract: The paper proposes a low-complexity direction of arrival (DOA) and angular spread estimation algorithm for coherently distributed sources. The proposed algorithm extend Root-MUSIC algorithm of the point sources to the diffuse source localization. According to the decoupled character of the spatial frequency model of generalized steering vector and the rooting polynomials which are obtained based the deterministic angular weighting function of the coherently sources, and the nominal DOAs and angular spreads can be estimated by iterative Root-MUSIC-like estimator. Without spectrum searching, the proposed algorithm provides a sufficiently good estimation accuracy as well as computational simplicity for estimating the nominal DOAs and angular spread. In addition, it can be applied to the scenario with multiple sources that may have angular distribution shapes. Simulation results illustrate the performance of the method.