This research is to study the components and stages of the ancestor spirits ceremony of the Phuthai in Tambon Khamcha-i, Amphoe Khamcha-i, Mukdahan. Data is collected by observation and interviewing 63 gurus, Chao Jum, Tiem and the Phuthai people who attend the annual ceremony. It is found that the components of the ancestor spirits ceremony are the people attending the ceremony including Chao Jum, Tiem and all of the Phuthai in Tambon Khancha-i. Chao Jum takes the most important role in the ritual because he is a chairperson and a mediator who communicates between the Phuthai and the ancestor spirits. Equipment and procedures in the ritual are oblations, sacrifices and containers for the oblations. The sacrifices which the Phuthai donate the money to buy are brought to practice at the Chao Poo Dan Tueng house and Chao Jum’s house every April 13th. The Phuthai ancestor spirits ceremony ritual has in 3 rites: the annual ancestors spirits ceremony, Karn Ba (a vow) and Karn Khob (Making a votive offering). The villagers believe that the ancestors spirits, called Phi Chao Poo, which is respectfully engaged from Muang Wang is the spirit of a past king of the Phuthai. Chao Poo always protects them and inspires seasonal rains for plentiful products so they hold the ancestor spirits ceremony ritual every year. If anyone does not pay respect or (disdain) him, Chao Poo will punish him with illness or death. The Phuthai in Tambon Khamcha-I have always clung to this belief and still practise it