Stable habitat provides sufficient food to sustain large species populations, and becomes a refuge under increasing environmental stress. Stable habitat also becomes a population source and re-expand hotspot once the stress decreases. Thus, identifying and protecting stable habitat is key to species’ long-term persistence. We identified the stable habitat for critically endangered western black crested gibbon (Nomascus concolor) in Mt. Wuliang, where one of two largest populations of this species lives in. We collected gibbon historical distribution data, and modeled the potential habitat in Mt. Wuliang during 2000, 2010, and 2020. We identified the stable habitat by overlaying the potential habitat layers from the three time periods and excluded habitat patches smaller than the species’ home range. Gibbon habitats continuously expanded from 2000 to 2010 (+13%), and from 2010 to 2020 (+6%), indicating that gibbon habitats are recovering at Mt. Wuliang. Stable habitat was 304 km2, mainly located at mid-elevation (2 100 – 2 600 m). Nearly all (99%) gibbon groups occupied stable habitat in each period at a mean density of 0.34 groups/ km2. Gibbon population density in the Wuliangshan National Nature Reserve (WNNR, 0.44 groups/ km2) was 83% greater than that density outside WNNR (0.24 groups/ km2). However, only 50% of stable habitat was within WNNR. Thirteen stable habitat patches located outside WNNR require urgent conservation interventions. Stable habitat in protected area is sufficient to ensure the persistence of these gibbons, but we still need to involve stable habitat outside protected area to sustain population recovery in the future.