Black-naped Oriole (Oriolus chinensis), Oriolidae, Passeriformes, is a member of old world songbirds. It has a wide distribution all over the eastern Asia, and is divided into 18 to 20 subspecies by differences in breeding sites, residents or migrants, morphological characters and songs. The populations breeding in Taiwan are classified as subspecies Oriolus chinensis diffusus. Black-naped Orioles inhabit in wooded habitats with a preference for tall secondary forests and disturbed wooded habitats and the staple foods of Black-naped Orioles are fruits, larvae, pupae and imagines of insects. This study was intented to understand the habitat preference and to explore the fundamental ecological data of Black-naped Oriole in Taiwan. Breeding seasons of Black-naped Oriole started from March and ended in July, and reached its peak from April to June. Most of the birds had two broods each year. Females built nests and incubated for 17-21 days alone, and males shared feeding and protecting juveniles after hatching. The birds of Pingtung population often built their nests on tall Albizia falcate and those of Fenglin population on Pachira macrocarpa. The breeding success was 23.3% in Pingtung and 18.2% in Fenglin. The breeding failure were due to human disturbance, climate, and poaching. The materials used for nest were bark, grass, leaves, and some artificial materials. Black-naped Orioles prefer to build nests at the same tree but on different branches. The nests were often closed to nests of Dicrurus macrocercus. Cooperative defenses between these two birds were observed.