Abstract: In rural family planning，grassroots governments bear the bottom line of dual responsibilities of birth control and social order，while farmers’growth bottom line is unbreakable. Grassroots government’s bottom line logic is rooted in the unilateral liability model built by pressurized system. Farmers’growth bottom line is rooted in rural social economic and cultural environment. There is a strong tension between the three bottom lines. Farmers evade ligation to stick to their bottom line and through the compromise strategy of gender selection to soften the regulatory pressure from the state. Grassroots governments and village representatives also follow the bottom line of farmers in the family planning work to relieve the tension between birth control and social order. Through the interaction between grassroots governments，village cadres and farmers，the bottom line logic of social governance is formed. Since all subjects follow the bottom line logic，rural family planning has achieved good results：the fertility national policy goals are achieved，the social order were not challenged by family planning，farmers’bottom line growth is maintained. Through the case of rural family planning，we can find out that all the subjects of social governance must stick to the bottom line logic，or the harmonious order can not be formed.

Key words: rural family planning, birth control, population control, social governance, the bottom line