Abstract: To deal with the issue that the long time accumulation method is hard to be applied to the detection and parameter estimation of Linear Frequency Modulated Continuous Wave (LFMCW) signal, a novel algorithm combining the joint inter-frame correlation method and cyclostationary method is proposed to detect LFMCW signal and estimate its parameters. Firstly, consistency of noise variance is completed by the normalized window-variant coherent average method. Then, on this basis, the period is exactly estimated with inter-frame correlation method. Finally, cyclostationary method is utilized to estimate the phase parameters of LFMCW signal. The proposed algorithm realizes long time accumulation with low computational complexity. For low Signal- to-Noise Ratio (SNR), this method still achieves good estimation performance. Simulation results verify the effectiveness of the proposed method.