The study aims to explore the impact of internal social capital banking on the operations of commercial banks in Vietnam. The study is executed in two phases. Phase 1 uses the expert method to build scales and design survey questions. In phase two, scale test and structural equation model analysis (SEM) are performed with a sample of 243 questionnaires for directors and deputy directors of branches of 32 commercial banks in Ho Chi Minh City. It also analyzes the contribution of the structure of the relational network within the bank and the quality of the relational network. The research results show that internal banking social capital affects all three operations; namely mobilization, lending and service provision of the banks. Based on the research results, the study proposes an analytical framework to improve the quality of internal banking relationships.