Upper echelon theory mainly explores the relationship between top management team characteristics and both strategic choice and firm performance. However, the relationship between the strategic choice and firm performance is not explored much yet. The purpose of this study is to test the possible mediating effects of strategic conformity on the relationship between top management team characteristics and firm performance. This research is trying to explain the impact of strategic conformity on firm performance through the behavioral theory of the firm, and to explore the possible mediating effect of strategic conformity furthermore. Based on the 33 commercial banks collected from Taiwan Economic Journal (TEJ) database between 2010 and 2011, the empirical results show that strategic conformity has the complete intervening effect on the relationship between top management team size and firm performance, and partial intervening effect on the relationship between top management team education and firm performance. This empirical result has important implications for both academia and practice.