Abstract: The radar used Linear frequency modulated continuous wave(LFMCW) signal can detect the information of range and Doppler of target. This paper analyzes the LFMCW signal used in HF radar, then deduces the expression of its beat frequency, and the theoretical for range/Doppler processing used two-dimensional fast Fourier transform(FFT) technique. The range/Doppler processing and the adaptive digital beamforming(ADBF) technique combined to extract the information of target echoes while control the effect of interrupt and noise. The simulation results are provided in this paper.