With the increasing application demands for radar jammers, traditional array designs and direction-finding algorithms exhibit critical limitations: excessive information redundancy in uniform arrays, restricted estimation accuracy due to limited physical aperture, and significant performance degradation when processing coherent signals. To address these issues, this paper proposes a coherent signal Direction of Arrival (DOA) estimation method based on spatial smoothing preprocessing and the MUSIC algorithm, integrated with a two-dimensional composite uniform arrays. The method aims to overcome traditional array design constraints and mitigate DOA performance deterioration caused by coherent signals. Specifically, the spatial smoothing technique leverages the translational invariance property of uniform arrays to effectively solve the rank deficiency in covariance matrices induced by coherent signals. The two-dimensional composite uniform array adopts a sparse array configuration to expand the effective aperture under the same number of array elements, thereby enhancing DOA resolution. Experimental validation combines two-dimensional spatial smoothing with the MUSIC algorithm for DOA estimation of coherent signals on the composite array. Results demonstrate that the spatial smoothing method successfully suppresses coherent signal interference, while the composite array achieves superior DOA estimation performance compared to traditional uniform arrays with identical element counts, validating the effectiveness of the proposed methodology.