Abstract: The range walk of supersonic weak targets is a serious problem in the long coherent integration time. And the traditional radar has poor detection performance on the targets of this type. To solve the problem, a detection and parameter estimation algorithm for the supersonic weak targets in the 2-D frequency domain is proposed. First the echo signal model of supersonic weak targets is presented, and the characteristic of range walk is analyzed. Based on this, the expression of the echo in the 2-D frequency domain is derived, and the linear connection between range frequency and azimuth frequency is obtained. Integration along the slanted line in the 2-D frequency domain is performed to detect the targets and the parameters are estimated. Finally, the performance of target detection and parameter estimation of the algorithm are analyzed by the simulation experiments, and theoretical derivation and simulation results suggest that the signal-to-noise ratio(SNR) integration gain of the algorithm is the product of pulse compression ratio and pulse number of coherent integration.