Taking the phenomenon of entrepreneurship among youth returning to L Village in Zhejiang Province as a case study， this research constructs an interactive analytical framework of “formal institutions-informal practices” to explain the mechanism and core logic of the “institutionalized reorganization” of rural social networks in the entrepreneurial process. Through the interaction of formal institutions and informal practices， the tripartite actors—the local government， entrepreneurial youth returnees， and the operating company of the entrepreneurial base—dynamically modify and reconstruct the existing rural social network， achieving its gradual transformation into an institutionalized entrepreneurial support social network. By empowering young entrepreneurs through policy and regulating interactions among actors within an institutional framework， informal relationships are transformed into institutionalized ones. Meanwhile， the operating company’s “weak management model” and its creation of “policy fissures” effectively bridge the gap between the government and the entrepreneurial youth， enabling the soft implementation of formal institutions and creating space for the informal practices of the youth. The institutionalized rural social network thus emerges as a multilayered collaborative model that integrates local social genes with modern market rules under the policy framework and connects actors through functional orientation. This structure enables young returnees to take strategic actions within the rural entrepreneurial field， thereby improving the outcomes of their entrepreneurial actions.