A total of 1,465 individuals from 58 species of wild orchids were found ranging from 72 to 696 orchids per trail.The number of orchid species was ranging from 7 to 30 species per trail.Sanyen nature trail had the highest number of wild orchid species, abundance and biodiversity index.Thirty wild orchid species of 697 individuals found in this trail provided the Shannon-Weiner index of 4.462.Various habitats of orchid in Khao Nan National Park were found.The specimens were classified into three groups: epiphyte, terrestrial plant and lithophytes.There were 35 epiphytic species belonging to 22 genera, 14 terrestrial species belonging to 13 genera and 2 lithophytes species belonging to 2 genera. This indicates that most of orchids at Khao Nan National Park were epiphytes.