Abstract: Based on linear frequency modulation (LFM) and stepped-frequency signal, traditional method to obtain the high resolution range profile will bring the problems of weaken scatters′ amplitude loss, range-Doppler time shift, and mainlobe broadening, thus a sparase signal processing model based on overcomplete and block sparse is indicated, then its sparse properties by using block orthogonal matching pursuit and block iterative soft thresholding algorithm are proved to realize high resolution block sparse imaging based on LFM and stepped-frequency signal. Simulation results show that compared with traditional methods, sparse imaging algorithm has better performance for the scenarios of multi-target and moving targets.