Nowadays, companies for adapt to changing conditions in the market and against competitors, to provide their survival in turbulent environment and better performance, are seeking to gain competitive advantage. Flexibility is considered as a competitive capability and makes companies respond to unforeseen situations and fast changing environments. The aim of this study is investigating the impact of strategic flexibility on market performance with mediating role of open innovation. In this paper, the external technology acquisition and external technology exploitation is considered as two aspects of open innovation. Current study in terms of purpose is applied and is descriptive-survey. To evaluate the hypothesis of 80 SMEs in the industrial zone of Rasht were examined and data analysis by structural equation modeling based on partial least squares (PLS) was carried out. The results showed that strategic flexibility has significant and positive impact on open innovation and also open innovation has significant and positive impact on market performance.