Abstract: Niche characters of the dominant plants and the feeding plants for Hainan black-crested gibbons, Nomascus hainanus in Hainan Bawangling National Nature Reserve were studied by plot survey to understand their adaptations to the environments and competitions. A total of 190 species were recorded in the plot with an area of 4 800 m2, of which 41 species, accounting for 21.58% and 58.89% in species number and importance value, respectively, were fed by the gibbons. There were only 24 plants or 12.63% of the plants with a niche breadth higher than 1, while other 166 plants or 87.36% of the plants with a niche breadth lower than 1. Among the feeding plants, there were only 13 plants or 31.71% of them with a niche breadth higher than 1, while other 28 plants or 68.29% of them with a niche breadth lower than 1. And among 17 species pairs with an overlap index higher than 0. 5, 12 pairs are both feeding plants. This study indicates that the current habitat of montane forest is less suitable for the feeding plants so to recover the lowland rain forest are suggested to carried out as soon as possible.