<p>As an essential infrastructure of mines, the instability of tailing reservoirs due to liquefaction can lead to significant losses. The gradual discharge and consolidation of tailings result in different tailings’ relative density modes. Based on practical cases, a study was conducted on the impact of different tailings’ relative density modes on the dynamic response of tailing reservoirs. The parameter calibration and numerical verification through laboratory tests and field surveys provided the foundation for the dynamic analysis and proved the correctness and effectiveness of the method. When defining the relative density according to the maximum, minimum, and linear distribution with depth, the response of acceleration and displacement is the strongest when distributed according to the maximum value, the weakest when distributed according to the minimum value, and the most significant response occurs at the dam abutment. The excess pore-water pressure ratio rises faster when distributed at the minimum value under the slope of the tailing reservoir. However, within the reservoir area, the excess pore-water pressure ratio rises faster when distributed linearly with depth in shallow areas, while in deep areas, it rises faster when distributed according to the maximum value. After considering the linear distribution of tailings’ relative density, the shallow buried area of the reservoir indicates an increased risk of local liquefaction; thus, it is essential to fully consider the different tailings’ relative density modes in the dynamic analysis of tailing reservoirs.</p>