Abstract: This study investigates the factors influencing the thermal insulation performance of Multi-Layer Insulation （MLI）, particularly focusing on layer density and the thermal conductivity of separator materials. Using a layer-by-layer model and simulation calculations within the temperature range of 20 K to 300 K, we explore the relationship between MLI's thermal insulation performance and these factors. Based on our findings, we propose a novel structure called Variable Density and Variable Separator Material Composite Multi-Layer Insulation （VDS-MLI）, which considers the temperature-dependent thermal conductivity of different interlayer materials. Under our simulation conditions, we find that VDS-MLI significantly outperforms traditional structures, with a 10% to 12% improvement in thermal insulation performance. This innovative approach holds promise for enhancing thermal insulation efficiency and offers new avenues for the design and application of multi-layer insulation materials, particularly in low-temperature environments.