Abstract: Aiming at the problem that the co-array has holes and cannot fully utilize the information of coprime arrays, a beam-space direction-of-arrival (DOA) estimation method for coherent signals based on coprime arrays is proposed in this paper. Firstly, the virtual array is constructed by using the difference set, and the traditional coprime array is transformed into a virtual uniform linear array by filling zeros at the hole positions. Secondly, the virtual linear array is divided into several overlapping subarrays, and the received data are transformed from the element space into the beam-space via beamforming. Then, the output covariance matrices in multiple beam directions are summed to construct the beam-space matrix, which achieves signal decorrelation and improves the SNR. Finally, it is combined with the subspace method to realize DOA estimation. The results from simulation experiments and lake trial data processing demonstrate that the proposed method has good directional estimation performance and exhibits good robustness in practical application scenarios, thereby validating its effectiveness and applicability.