Frequency-modulated continuous-wave （FMCW） radars utilize the frequency difference between the transmitted signal and the received echo signal to calculate the target range， so estimating the beat frequency is an important procedure in FMCW radar. However， the interference of negative frequency component and the multi-frequency component deteriorate the accuracy of frequency estimation in practical application. In this paper， a new frequency estimation method is proposed for multi-frequency estimation， which is based on the Orguner method and iteration. The method can accurately estimate frequency only using three discrete Fourier transform （DFT） samples near every frequency component. Simulations confirm that the proposed method outperforms traditional alternatives both in noiseless scenario and Gaussian white noise scenario， and has lower complexity because of no windowing processing.