In the time when there were no characters or those who can be literate are so few, people handed their story down from mouth to mouth, and the story tellers(later reciter or singer) would put the historic scene, Episodes or accidents of their times into their story help their listener understand more and make them interesting. Therefore, their society` s value was reflected in the oral traditional literature of epos. The story of Khunchang Khunphaen, one of the great works in thai literature is a true triangular love story between three persons, a beautiful woman, Wanthong and two lovers, Khunchang and Khunphaen. This story would be handed down orally by story tellers for about 500 years in front of crowds on festival days, and it was recollected and born as a perfect literature work by Rama the VI in 1917. The object of this study is the reconstruct of society at that time through the study about the ways of life and social conceptions and beliefs in the work "Khunchang Khunphaen," so there are some conclusions. First, Thai was more prefer to be government officials than any jobs. They believed that good jobs brought honor or fame and wealth. This is changing now around the educated class in a big city while industries develop and jobs specialize. Second, at that time, incantations was widely liked and believed, People told fortune with their dreams or peculiar changing of animals and plants and use charms and amulets. This is supported by many characters who use incantations in this story. Now, incantations like amulets, charms still have survived. Third, in the era of the Kingdom of Ayuthia entering the novice-hood for 6-13 years old boys was thought be regarded as the pursuit of learning such as reading, writing and composing, which is regarded as one way of being government officials. This is supported by that only educated class could enter government service. Now this inclination was partly not changed but a Buddhist temples have turned into a school, and unscientific curriculums like inclination was gone since Rama the V. Forth, the era of the Kingdom of Ayuthia was the society of Brahman culture, specially, the high society was. So ceremonies related to Royal family was Brahman` s ceremony. And now that Brahman` s was changed to Buddhist monk` s ceremony or concepts of the two culture have been mixed. Fifth, the ways of life of thai in Ayuthia which was mentioned in this story was not changed much now. Only unscientific and insanitary factors was modernized. Sixth, thai women regardless of her social position could be sold with loans, bestowed as gift or reward or was married to a man disregarding woman`s will. So it was natural to buy and sell women freely. Now it is almost rooted out, but it was thought that bad custom of past still survive little now because buying and selling people(especially woman) happen frequently.