Abstract: Rayleigh wave detection, which is characteristic of being nondestructive, fast, economical, convenient, has been used widely in some engineering field such as earth exploration. The accurate extraction of dispersion curve is the key technique in Rayleigh wave exploration and damage detection. In this paper the dispersion curve extraction of Rayleigh wave in pavement void detection is studied by theoretical analysis of different dispersion curves extraction ways, and processing experimental data by τ-p conversion and f-k conversion. The comparison of the two handling methods is given and f-k conversion is better than τ-p conversion in pavement void detection. There are theory and application benefits for dispersion curves extraction of Rayleigh wave in pavement void detection.