<p>Due to the limitation of hardware architecture, traditional methods can not be applied to the existing radar to achieve performance upgrade. Therefore, it is necessary to study a DOA estimation method that can improve the estimation accuracy without changing the hardware structure of the existing radar equipment. In this paper, we model the output data processed by the beam-forming method as windowed Discrete Time Fourier Transform (DTFT) bins. In this way, we transform the problem of accurate DOA estimation using the output of the beam-forming method into the problem of accurate frequency estimation using the windowed DTFT bins. We establish several linear equations to describe the correspondence between DTFT bins and frequencies. Based on the above correspondence, the DOA of a single target can be estimated using any three bins. Furthermore, we propose a performance improvement strategy using multi-snapshots. Theoretical analysis and simulation results show that our method has higher anti-noise performance and better estimation accuracy, with one order of magnitude improvement in accuracy, compared to the IpDTFT method.</p>