In Thailand, There are around 2,000 places of wall painting including cave arts from prehistoric periods. Most of them are in the Ubosot (ordinary hall) or in the chamber of prang: the main shrine of the temple and some of them are in the cave. The oldest wall painting in the ordinary hall is in Sukhothai period in 13th century. Even though they have a conservation by Fine arts Department but in many case has a serious deterioration condition because of the humidity problem. The lower part of the Ubosot; supporting layer was gentle and the colour layer was flake off. So we are unavoidably lost a lot of great Thai traditional arts by this cause all the times. Although, Conservation in Thailand was set up moreover 40 years ,but we are a lack of scientific knowledge and the new techniques to cope with this serious damage. 10 years of my working life in conservation of painting and sculpture group I was found many problem …………