To reveal the distribution characteristics of riprap layers and silt pockets in reclamation projects, the study investigates the application of Natural-source Seismic Frequency-domain Imaging technology based on the reclamation project of Dalian Jinzhouwan Airport. After parameter testing, a 2 m track spacing and a 20 min collection time were used for detection study. The result shows that the riprap layer is primarily characterized by high-frequency amplitude, while silt exhibits low-frequency amplitude features. Comparison with borehole data indicates that, in this study, the average absolute error of this method for detecting the riprap layer thickness was controlled within 1 m, which proves the reliability of the method.