This study takes Liangshan Prefecture，a poor mountainous area in Sichuan Province，as a case area to analyze the impact of social capital on farmers’ livelihood strategies. The following results and conclusions were obtained：i. Different types of social capital had different effects on the livelihood strategy of famers，and they had obvious spatial differences. Individual social capital，categorized into traditional and expanded social capital，had a positive effect on non-agricultural livelihood strategies. The effect of traditional social capital was the most significant in the high mountain villages，followed by the semi-mountain villages，and the river valley villages was non-significant. The effect of expanded social capital was the most significant in the river valley villages，followed by the semi-mountain villages，and the high mountain villages was non-significant. The collective social capital with the Peasant Economic Cooperation Organization （PECO） as a carrier had a negative effect on the non-agricultural livelihood strategies of farmers；however，this was only significant in the river valley area. ii. The income differences among the different livelihood strategy types were explained by the livelihood strategy choices of farmers. As non-agricultural work can bring more benefits，the labor force exhibited one-way migration from villages to cities，resulting in a lack of the subject of rural revitalization. It is necessary to implement effective measures to highlight the role of PECO in increasing agricultural income for farmers. Finally，based on the above conclusions，policy recommendations with respect to livelihood transformation of farmers and rural sustainable development are discussed.