Abstract: The legendary of Urangadhatu: The Refection of Cultural in Mekong basin. This qualitative research used 15 issues of the legendary of Urangadhatu. The researcher aimed to study 3 purposes: studied the history of the legendary of Urangadhatu, studied the contents of the legendary of Urangadhat and studied the refection of cultural in Mekong basin the shown in the legendary of Urangadhatu. The research used structural-functionalism and cultural ecology as the main research theories, used reflection theory, semiology and myth as the supplement theories. The research founded that the legendary of Urangadhatu is the literature was extensive in all Mekong Region, since, 22th Buddhist Century in Lan Chang Royal Court. The research gathered 3 stories included Religion Fairy Tale, Natural Fairy Tale and Urangadhatu Tale. Took the story of the traveled of Lord Buddha to Mekong basin, the history Lan Chang Kingdom and life of people in Mekong basin then compiled to the legendary of Urangadhatu. The continuity followed the form of Buddhist literature to shown the right of being the King of Lan Chang Kingdom that had the reincarnation life. The stories that found in legendary of Urangadhatu extensive for long period of times and shown the reflection of history that disguised in the legendary and explained about the holy areas and the faith of the people in Mekong basin. The legendary of Urangadhatu was the great legendary that shown the reflection of humans and their geography, social and the spirit that reflect the cultural of people in Mekong basin up to now.