With the acceleration of major projects and new urbanization processes, shallow natural gas in the Yangtze River Delta region, characterized by its wide distribution and shallow burial depth, has an increasingly prominent impact on geological hazards related to engineering construction and underground space development. To quickly identify its distribution and stratigraphic horizons and provide technical support for engineering geological surveys and risk prevention/control, this study, based on the differences in resistivity physical properties between gas-bearing sand layers and water-bearing sand layers, employs the high-density resistivity method combined with borehole verification and 3D spatial interpretation technology. High-density resistivity survey lines were deployed in a specific area of the Yangtze River Delta. Leveraging the method's advantages of low cost and rapid deployment, and utilizing the characteristic that gas-bearing sand layers exhibit high resistivity while water-bearing sand layers exhibit low resistivity, the stratigraphic structure and gas-bearing sand layers were detected. 3D spatial interpretation was then achieved through a 3D visualization platform. The results indicate that the electrical structure of the shallow strata in the study area can be divided into four layers, with the resistivity characteristics of each layer as follows: Layer ① has a resistivity of 15~40 Ω·m; Layer ② has a resistivity of 20~50 Ω·m, generally higher than 25 Ω·m, corresponding to a gas-bearing sand layer primarily distributed at a shallow burial depth range of 9~22 m, which poses certain impacts on engineering construction; Layer ③ has a resistivity of 10~20 Ω·m; Layer ④ has a resistivity of 5~15 Ω·m. The high-density resistivity method combined with 3D modeling technology can effectively achieve the spatial positioning of shallow natural gas reservoirs and accurately interpret the distribution range and scale of gas-bearing sand layers, providing efficient and low-cost technical support for engineering geological surveys in the Yangtze River Delta region.