Abstract: To be aimed at the three problems of the Minimum Variance Distortionless Response (MVDR) method:not suitable for the broadband, complex computation, how to combine with sonar system in existence, this paper brings forward a broadband beamspace high resolution direction-of-arrival estimation method based on sub-band decomposition. It uses the method of sub-band decomposition to realize the expansion of MVDR under broadband condition, uses the beam transforming to realize the dimension amount of calculation reduction as to reduce the amount of calculation and improve the stability of the algorithm, and brings forward a new method to combine this technology with the sonar system in existence, using the direct output of the sonar multi-beam system, which can reduce the computational complexity and leave out the transforming from the array element to beamspace, the method of which can replace the conventional split-beam direction-of-arrival estimation system or the single beam system, which can improve the performance of the whole sonar direction-of-arrival estimation system. After theoretic analysis, simulation and authentication in lake, the method proves to be simple, effective and practical.