The article focuses on the impact and Acceptance of Hindu culture in Modern Southeast Asian Buddhism. The purpose of this study is to examine critically the influential epic Ramayana on Siam culture, Thai Ramayana version 'Ramakien', reveal instances of Buddhist Modification. The Ramayana by the great sage Valmiki is considered by Indians to be the first great literary work to be produced in India. The influence of this work is to be seen not only through centuries but even in other countries, such as Thailand where there are modified modern versions. In this paper, I have three objectives : (1) I may discuss the epic Ramayana of India gave birth to the Ramakien of Thailand. In modern times Valmiki's epic was made to fit the spiritual trends current in the new Chakri dynasty, which were themselves based on Brahmanic tradition and Theravada buddhism. With regarding to the structure of the Traibhumi cosmography, and the relationship between merit and power implied by this cosmography ranks all beings from demons to deities in a hierarchy of merit which accrues according to karma the actions of past lives. (2) I analyze how to have attempted to dissect the Hindi and Thai version of the Ramayana. The Hindu concept of kingship is also depicted in the life of Rama. The Hindus see in Rama the norm of a true Hindu life characterized by the Caste and Dharma. In Thai transformed version, it does not preach Hindu values of personal or social life. The Ramakien emphasized that the Buddhism were higher than all other laws, and that the King is regarded as the incarnation of Phra Ram, and thus is also the narration of the righteous buddhist ruler. (3) I discuss how cultural or social contexts can influence the structure of the royal Wat. The whole epic was painted by the order of Rama I in the galleries of the Wat Phra Keo. In other words, it is the very centre of the dynastic cult enshrining the Emerald Buddha, the most iconic expression of the Ramakien tradition were officially amalgamated. Rama I was continued the process of elaborating and stabilizing the complex religious pattern, with Buddhism at the pinnacle. My finding will support the idea that the Ramakien is particularly appealing to the Thai people because it presents the image of an ideal king, Rama, who symbolizes the force of virtue or dharma while Thotsakan represents the force of evil. Eventually the force of good prevails. Being Buddhists, the Thai poets bring into the story the Buddhist philosophy(especially, the law of cause and effect, karma). This paper examines the role of the Hindu epic Ramayana in the historical and cultural contact between Hindu India and Buddhist Southeast Asia. It should now be possible to evaluate what elements of Hindu culture were transmitted into Thai through the Rama story.