Abstract: Based on a sparse and nonuniform concentered orthogonal loop and dipole(COLD) array,an algorithm of estimating polarization signals' direction-of-arrival(DOA) without ambiguity is proposed.Because of exploiting the characteristics of the sparse and nonuniform COLD array,such as the big array aperture and the little number of sensors,the proposed algorithm has higher DOA resolution in case the number of sensors is limited.Since the COLD array is divided into loop subarray and dipole subarray,the ambiguity of estimating DOA based on each subarray is analyzed.Thus,the condition of DOA estimation without the ambiguity is presented based on a sparse and nonuniform COLD array.The validity of the proposed algorithm is testified via simulations.