During field surveys of habitat use behaviours of Hoolock gibbons (Hoolock hoolock), 30 used sites and 30 corresponding available sites were established in Nankang, Mt. Gaoligong, from 24th March to 6th May, 2006. Results indicated that Hoolock gibbons tended to inhabit eastern slopes (Ei=0.344) as they were relatively windproof. They also favoured the tree species Querucus acutissima (Ei=0.455) and Eurya pseudocerasifera (Ei=0.068) for their large crown, as they provide more continual movement routes and large spaces for the gibbons, compared with other plant species. Quantitative factors showed that a total of 12 factors (slope; average tree and bamboo height, average circumference of tree at breast height (ACTBH); tree and shrub coverage; tree, bamboo and lianas density; and distance to water, roads and fields of Fructus amom), were significantly different between used and available sites, which revealed high selectivity to the spatial structure of habitats. Stepwise discriminant analysis showed that slope, ACTBH, bamboo density, distance to water and average tree height were the key factors, discriminating used sites from available sites, accounting for 98.3% of correct classifications. Optimal habitats of the arboreal Hoolock gibbon were characterized by having connected crowns of tall trees (14.14±3.19 m) with large basal area (ACTBH: 90.72±26.12 cm), steep slopes and high bamboo density, providing reduced ground disturbance and plentiful food for Hoolock gibbons in spring.