Epiphytic orchids grown on the tree trunks and branches might expose to the sunlight more than on the forest floor. Light is a limiting factor for the growth of most orchids. The continuous wet and warm climate of Khao Nan National Park possibly makes the existence of epiphytes. The most common epiphytic species found belong to genus Dendrobium . Wild orchids were classified based on their habitat, 62% (48 of 77 records) of them were the epiphyte which lived on the trees while 25% of them were lithophytes and the others lived on another types of habits. Bua Chak Yai trail is the nature trail having most diverse habitat types. At this nature trail, there were five habit types: epiphytes (E), terrestrials (T), lithophytes (L), epiphytes and terrestrial orchid (ET) and both of epiphytes and lithophytes (EL). There were four habit types at Thaton – Yodnam nature trail and three habit types at Hui Lek, Sanyen and Thaton – 1400 m Peak nature trails.