Rural revitalization cannot be separated from returning home to start a business，and the social capital accumulation of entrepreneurs has become the key to the success of returning home entrepreneurs. Based on the survey data of 2，139 returning start-ups in 2019，this paper divides social capital into two dimensions of strong and weak relationship network by using ordered Logistic model and mediating effect model，and studies the impact of social capital on the business performance of returning start-ups.The results show that both strong and weak relationship networks can significantly improve the business performance of return-home start-ups on the whole. Heterogeneity analysis shows that strong relationship network has a more significant effect on the business performance of survivable returning entrepreneurs，while weak relationship network has a more significant effect on the business performance of development-oriented and value-oriented returning entrepreneurs. Weak relationship network has a significant positive impact on the business performance of returning start-ups in the eastern and central regions，while strong relationship network has a significant positive impact on the business performance of returning start-ups in the central region. Moreover， weak relationship network has a more significant effect on improving the business performance of returning start-ups in the second and third industries. In addition， The mechanism analysis shows that innovation spirit is the mechanism of social capital promoting the improvement of business performance of returning start-ups. Therefore， it is suggested that the government should build a platform to promote the communication between returning entrepreneurs，striving to achieve the dual embedding of the strong and weak relationship between returning entrepreneurs，and attach importance to cultivating the innovative spirit of returning entrepreneurs.