An angle estimating method applied in a radar system. The radar system includes a first antenna array including M antennas. The angle estimating method includes steps of obtaining a plurality of beamforming weighting vectors; receiving signal from M antennas and forming a received vector; performing an augment operation on the received vector and obtaining an augmented received vector; computing correlation between the augmented received vector and the plurality of beamforming weighting vectors and obtaining a plurality of results accordingly; and determining an angle-of-arrival of an object according to the plurality of results.