Abstract: In airport construction in mountainous areas, there is an ultra-high-steep (100-m slope ratio less than 1:1) reinforced soil-filled slope scheme, but there are few studies on the stability of this kind of slope. Taking the ultra-high-steep reinforced soil-filled slope scheme of an airport in Yunnan Province of China as an example, through the large-scale geotechnical centrifugal model tests and numerical calculation, the stability of the reinforced soil-filled slope under natural conditions is studied. The main results are as follows: (1) The deformation and failure of the slope include local cracking of filled soil, panel bulging and slight extroversion of piles, and the displacement of pile top does not exceed the allowable design deviation. (2) The displacement of the slope at the top is mainly subsidence, with the maximum subsidence at the mouth, and there are settlement and lateral horizontal displacement in the lower and middle parts of the slope at the interface between the reinforcement and the foundation at the steep terrain. The deformation of the slope meets the requirements of the specification. (3) The soil pressure inside the filled slope is lower, and that in the middle part of the slope is the greatest. The axial force basically meets the design requirements, while that of a small number of reinforcement bands at the interface between the reinforcement and the foundation exceeds the design value (less than 4%). The study shows that the overall stability of the ultra-high-steep reinforced soil-filled slope is better. However, the filled soil in the mountainous airport is an inverted triangle terrain, and there exist local hidden dangers in the middle and lower parts of the slope (where the terrain of foundation surface changes steeply and the reinforcement band shortens). Subsequently the schemes should be optimized so as to further improve the local stability of the slope and the internal stability of the reinforcement soil. The relevant achievement may provide reference for the stability analysis of ultra-high-steep reinforced soil slope of mountainous airports and other similar centrifugal model tests.