Thousands of deep seismic sounding profiles have been obtained worldwide to detect crustal and lithospheric structures; unfortunately, fine near-surface/shallow sedimentary structures are difficult to determine through large-scale seismic surveys. To improve the near-surface/shallow sedimentary structure resolution, we extract multimodal dispersion curves with the frequency-Bessel transform (F-J) method from deep seismic sounding profiles in the Atlantic coastal plain and explore the joint inversion of multimodal dispersion curves and refraction. Three-layer sedimentary structures of the Atlantic coastal plain, which are highly consistent with drillhole data, are obtained by joint inversion with the Monte Carlo method. In the preferred sedimentary structure, the second layer of the models is identified mainly by the P-wave refraction, while the velocity discontinuity and shallower velocity are sensitive mostly to the multimodal dispersion curves. Although the dispersion curves are not sensitive to the second layer of the models, the pattern of the F-J spectrogram can be greatly influenced by the second layer. The preferred sedimentary models exhibit an extremely low sedimentary Vp/Vs ratio, which has a profound influence on the dispersion curves. The inversion of dispersion curves would lead to incorrect results without the Vp/Vs ratio constrained by P- and S-wave refractions. These results demonstrate that the F-J method is an effective approach to extract multimodal dispersion curves from deep seismic sounding data and that an accurate fine sedimentary structure can be obtained by the joint inversion of multimodal dispersion curves and refraction.