[in Thai language with English abstract:] Six hundred and eighty-six lichens specimens in family Graphidaceae on rocks and plants were collected from 7 forest types, coniferous forest, dry dipterocarp forest, dry evergreen forest, lower montane rain forest, lower montane scrub, mixed deciduous forest and tropical rainforest, in Phu Luang Wildlife Sanctuary, Loei province between June 2008 and November 2009. They were identified into 96 species 14 genera: Carbacanthographis, Diorygma, Dyplolabia, Fissurina, Glyphis, Graphis, Hemithecium, Phaeographis, Platygramme, Platythecium, Sarcographa, Sarcographina, Thalloloma and Thecaria. Nineteen species were new records to Thailand and 50 species were expected to be new species to science. The highest density of lichen taxa found in lower montane scrub. Dyplolabia afzelii and Sarcographa labyrinthica are common species. KEYWORDS: lichen, Graphidaceae, lower montane scrub.