Published information on Rotifera of Hainan Island is fragmentary, and more species than currently recorded may be expected. This contribution is part of an ongoing investigation to examine the species composition and distribution of the Rotifera from a wide range of freshwater habitats on Hainan Island. Species new to China are described based on material (parthenogenetic females) obtained from Hainan Island. Qualitative sampling of the littoral zones of reservoirs, ponds, temporal ponds, brooks, rivers and rice fields on Hainan Island, was carried out in November 2010, May and August 2011. About 134 samples were collected from 134 freshwater habitats (Fig. 1) using 35 μm plankton net, and preserved in 5% formaldehyde. In most localities, temperature and pH were measured. Twenty-five species of the genera Brachionus were identified (Table 1). Brachionus donneri bifurcus, B. huangi and B. murphyi are endemic to the Oriental Zone. Brachionus quadridentatus mirabilis, B. dichotomus reductus, B. dimidiatus, B. huangi, B. lyratus, B. leydigii rotundus and B. sericus are new to Hainan Island. Brachionus quadridentatus mirabilis, B. dichotomus reductus and B. dimidiatus are new to China. Brachionus quadridentatus mirabilis was collected only from a small pond (pH 6.7) with extremely long median anterior, posterolateral and foot-opening spines (Fig. 2). Brachionus dimidiatus was collected only from a small pond (pH 8.6) with Eichhornia crassipes. Its lorica has no caudal spines, and very short spines on the anterior margin (Fig. 3). Brachionus dichotomus reductus was collected from a reservoir (pH 7.2) with much elongated median anterior spines and long caudal spines (Fig. 4). Brachionus quadridentatus quadridentatus, B. calyciflorus, B. falcatus and B. angularis are the most common species in this genus. There are twelve cosmopolitan taxa, eight tropicopolitans taxa and five pantropical taxa on Hainan Island, and the biogeographical affinity of Brachionus has a circumtropical or cosmopolitan distribution. Diversity of Brachionus is much higher on Hainan Island than that in other six regions of China (Guangdong, Hubei, Shanghai, Xizang, Beijing and Jilin), and the species richness is negatively related to latitude (Fig. 5). Bray-Curtis dissimilarity of Brachionus between Hainan Island and other six regions of China varies from 0.17 to 0.54, and increases as latitude increase (Fig. 6).