Based on field investigation,specimens and literatures,the diversity of Orchidaceae in Qomolangma National Nature Reserve were studied.It shows that 63 species discovered by investigation fall into 35 genera,in which terrestrial were dominant with 42 species,followed by epiphytic with 19 species,and saprophytic with 2 species;The geographical elements of genera are divided into 10 types and 2 variants,which are dominated by North Temperate (33.3%) and Tropical Asia (21.2%);The geographical elements of species are divided into 5 types and 1 variant,dominated by SinoHimalayan.The Orchid floristic composition has a close relationship with Mt.Namjagbarwa region,following by the Jiuzhaigou National Nature Reserve and Gongga Nature Reserve.It also associates with Qinling area and Mount Xiaoheishan Nature Reserve.