The paper studies the effect of social capital on the firms’ debt capacity and capital structure in China. We measure the social capital of China’s 31 provinces through four indexes: the number of NGOs per capita, the index of trust among peoples, the volunteer blood donation ratio of civics, and the money and material donation of civics. The results show that in those areas with more social capital, the firms are more likely to have higher debt ratio and longer debt maturity, and the firms can get debt financing with less tangible assets. And in those districts, the firms are easier to obtain bank credits and trade credits. The paper has two contributions to the economics literature: first, it confirms the economic value of social capital from a micro view; second, it provides a new perspective to understand the firms’ capital structure choice.