The purpose of this paper is to study the relationship of knowledge sharing in organization on the success of talent management system with considering the social capital in petroleum industry. The main question in this article is "How can we implement TM and knowledge sharing by using their relationship"? The results showed that it happens via social capital. For this purpose, 3 questionnaires for evaluating TM, knowledge sharing and SC were distribute among 174 of human resource managers and experts in the staff divisions of Iranian National Petroleum Company and its affiliated branches located in Tehran by using randomized classification method. Finally, 62 people with sample formula were selected. Among them, 57 were returned (35% of the population). Analysis of data via structural equation model (SEM) supported the mediator role of SC on the relationship between TM and knowledge sharing variables. It means that focus on social capital and employing it in organizations can affect the success of implementing TM and knowledge sharing variables in organizations.