Abstract: When the array is overloaded, the commonly used high-resolution direction finding algorithm becomes invalid. Aiming at this problem, a novel direction finding algorithm for wideband sources was proposed. The algorithm used fourth-order cumulant based on minimum-redundancy-linear-array (cum-MRLA) to expand the array aperture. After removing the redundant information in the obtained fourth-order cumulant, it constructed a new Toeplitz matrix. The new matrix made full use of the information including in the original covariance matrix, and avoided the redundant information. Through theoretical analysis and computer simulation, the extended array aperture, the direction finding performance, detective probability and the most identifiable source number were studied. Results show that, compared with the minimum-redundancy-linear-array (MRLA) and uniform linear array with the same element number, the proposed algorithm has much larger array aperture and higher resolution, using M elements, which can identify M²-M sources.