With regards to the regional differentiation of folk beliefs, most of previous researches focus on the large scale regions in which there are clear differences in dialects. Within the small scale regions which belong to villages in the same town and have no difference in dialects, people still have different gods. In this paper, niche theory and niche breadth measure model are used in the micro-analysis of folk belief differentiation in three different villages in Quanzhou Donghai Town, which are Xunpu, Baoshan and Fashi. The results show that in such small scale regions with no difference in dialects, the most important factor which influences gods' niche breadth is the correlation between gods' functions and the industries in the regions. In the region, the gods' influence, distribution and function changes are all dominated by the law. The Gods' regional differentiation due to the gods' niche breadth correlates with the differentiation of regional industries. Differentiation of regional industries is formed by geographical conditions. Therefore, the regional differentiation of the gods with specific functions is closely related with the natural geographic environment. Agricultural Gods dominate agricultural regions while gods who bless the safety of seafaring dominate regions with industries regards to marine transport and fisheries. In the transitional zone, two types of gods' niche overlap and change with competition. In small scale regions, gods with universal functions have smaller niche breadth than those with functions which are highly related with regional economy. But in large scale regions, gods with universal functions have larger niche breadth than others. In the same region, god's niche breadth changes with changes of god's functions' and regional industries. The same gods in different regions have different niche breadths according to their functions and main regional industries. The results of folk gods' niche breaths which are calculated with niche breadth model accord with the influence and distribution of gods in three villages which confirms the feasibility of applying niche theory to the regional researches of folk beliefs.