The paper’s research results show that fall of birthrate can significantly increase urban and rural families’ per capita income and reduce Engel’s Coefficient，which indicates that population policy has significant poverty reduction effect on increasing family income and reducing family expenditure for food consumption. Compared with other provinces in Western China，fall of birthrate plays a more active role in increasing urban and rural families’ per capita income and decreasing the Engel’s Coefficient in the 8 provinces and regions with ethnic minorities，of which，those in the Northwest report better situation than those in the Southwest. Population policy has limited poverty alleviation effect in the 8 provinces and regions with ethnic minorities in Western China.