Laos, a landlocked country in Southeast Asia, has most extensive network of ecosystems in the Indochina Peninsula, surrounded by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west. It is the tropical vegetation and warm climatic conditions influenced by monsoon. Such geographical and climatic condition is favorable for the diversity of insects. However, research or educative investigation on insects have been poorly conducted. Through recent expedition during dry season (between December 2012 and February 2013), mainly held at Phou Khao Khouay National Park (PKKNP), which varies from sheer sandstone cliffs and pristine river gorges to rough mountain slopes along the Mekong river, we recognized atotal of 88 lepidopteran insects belonging to 22 families, Arctidae, Attevidae, Choreutidae, Cossidae, Crambidae, Geometridae, Gracillariidae, Hesperidae, Hyblaeidae, Limacodidae, Lycaenidae, Lymantridae, Noctuidae, Nymphalidae, Oecophoridae, Papilionidae, Pieridae, Pyralidae, Scythrididae, Sphingidae, Uraniidae and Zygaenidae, were recognized.