High linearity and low noise are important conditions for high-resolution imaging in wideband linear frequency modulation (LFM) radar systems, where stretch processing is commonly adopted. However, in practice, hardware may introduce amplitude and phase distortions to radar signals. The distortions will increase the range sidelobes (RSLs) of the dechirped returns and cause the decline of imaging quality. Traditional time-domain RSL correction methods are greatly influenced by time delay and can only be used in a small range window. To solve the problem, we propose a novel frequency-domain RSL correction (FDRC) method in this paper. For FDRC, we first multiply the extracted distortion and the stretched return by a baseband LFM signal and then perform the correction in the frequency domain. Both theoretical and simulation results show that the proposed method provides equivalent performances in RSLs compared to other existing distortion correction methods in a large range window. Besides, the proposed method can be much easily implemented in practical radar systems.