Due to the intense competition and rapid change in the market, partner relationship has become a critical key to corporate success. To sustain competitive advantage, firms have to build up valuable relations with partnerships. The aim of this paper is to explore the relations of long-term orientation for partnership and inter-organizational performance. This paper applies social exchange theory, resource dependency perspective and transaction cost theory to investigate the nature of and the factors affecting partner relationship. We derive an integrated model, which indicates two important factors affecting partner relationship: inter-organizational mutual trust and inter-organizational dependency. We find long-term orientation for partnership, inter-organizational mutual trust and inter-organizational dependency all affect inter-organizational performance.