Abstract: A new line-spectrum detection algorithm is proposed based on the matching extent of high-resolution and low-resolution power spectrums.For a certain data section,the high-resolution power spectrum is firstly estimated as a template,and then several low-resolution power spectrums are estimated and compared with the template to verify the line-spectra.Under the condition of sinusoid signal mixed with Gaussian white noise,the detection rate and the false alarm rate of this algorithm is deduced theoretically and proved by the Monte-Carlo simulation.In comparison with the conventional methods,this algorithm doesn’t need any information of the noise power spectrum and has constant false alarm rate.In the application of vehicle long-distance detection,this method achieves satisfying performance.