This is an important historical event in which Christianity entered Taiwan's aboriginal society, especially in the 1940s ~ 1960s, it was called "Missionary miracle of the 20th century ." The Seediq was also influenced by foreign belief culture, which has changed and weakened the traditional culture of the Seediq. From their 'Utux' of belief to explore their life ethics, this study attempts to identify the influence of foreign beliefs on the traditional beliefs of Seediq by interview, collect relevant materials and literature review. This study finds that foreign beliefs affect the traditional beliefs of Seediq, including hunting culture, values of funeral and values of traditional belief. The result that the traditional beliefs of the Seediq have gradually weakened and integrated with the foreign belief cultures.