Capillary trapping is an important strategy to prevent CO₂ from escaping. Meanwhile, under immiscible conditions, CO₂ may travel upwards by gravity. Studying the long-term effects of gravity and layered heterogeneity on CO₂ transport is crucial for ensuring CO₂ storage security in aquifers. In this work, fluid flow experiments driven by inertial force and gravity are conducted in a specially constructed layered sandstone. Whether driven by inertial force or gravity, the variation in CO₂ distribution in the high-permeability layer is consistently the most significant factor. In the low-permeability layer, the saturation and capillary pressure distribution of CO₂ clusters vary less and the geometric shapes are also more complex, thus the CO₂ capillary trapping in this layer is more stable. This work demonstrates that the low-permeability layer can effectively prevent CO₂ from escaping upwards when the permeability ratio between layers approaches two.