The problem of across range unit walking can deteriorate the performance of Orthogonal Frequency Division Multiplexing (OFDM) modulated radar in high-speed weak target detection.Therefore,a high-speed weak target detection algorithm for OFDM radar is proposed based on Prewitt operator and Radon transform.Firstly,the problems of across range unit walking caused by multi-pulse accumulation and of the noise interference on Radon transform are analyzed.Then,the Prewitt operator is used for convolution operation to suppress noise and retain echo energy,and Radon transform is used to accumulate energy along the range unit walking diagonal.Theoretical analysis and simulation results show that:Compared with Hough transform and Moving Target Detection (MTD),the proposed algorithm has better high-speed weak target detection performance at low Signal-to-Noise Ratio (SNR),and it can effectively achieve multi-target detection.