Abstract: Most salt mines in China are characterized by high impurity and multi-interlayer, and the salt cavern is almost filled with sediments from solution mining under extreme conditions. In order to evaluate the feasibility of building sediment gas storage in this kind of salt mine, an experimental study on the gas storage capacity of full-cavern sediments was carried out based on the Dawenkou salt mine in Shandong Province. Firstly, the representative sediment samples of this region were prepared, and the experiments of sediment gas injection and brine discharge in a single cavern under compaction conditions were carried out. It was found that the void ratio among the sediments for gas storage was up to 45.2%. Secondly, the optimization experiment was carried out for gas injection and brine discharge by the U-shaped cavern, and thus the optimal gas injection and brine discharge mode of drilling a horizontal brine discharge well to the bottom of the U-shaped cavern was determined, with the on-site implementation scheme provided. Finally, a gas storage model was established for the full-cavern sediments. The gas storage volume of well group B5 was estimated to be 30.7×10⁴ m³ according to the experimental results and field data. The results show that the sediments in this area have good gas storage capacity, the target well group has a large gas storage volume, and it is feasible to some degree to build sediment gas storage. Generally, the study results could provide a reference for the construction of gas storage in the Dawenkou salt mine and other such high-impurity multi-interlayer salt mines in China.