In the situation of increasing uncertainty, as an important financial institution, the risk-taking behavior of banks will directly affect the investment efficiency of enterprises, and then affect the macro-economy and systemic financial risks. The paper analyzes the impact of bank risk-taking on the investment efficiency from both inside and outside the balance sheet, and explores the impact of bank risk-taking on the investment efficiency under economic uncertainty. The empirical results show that whether the bank increases the on-balance sheet risk taking or off-balance sheet risk taking, it will increase the firm’s inefficient investment. Affected by the uncertainty of economic policies, bank risk-taking mainly reduces the excessive investment of enterprises to alleviate the inefficient investment. It is important to note that although most firms are underinvested, bank risk-taking does not have a significant impact on them. At present, we should improve the unified risk control system of bank financing on and off the balance sheet, and strengthen the role of supporting the real economy.At the same time, more measures such as market, economy and technology should be adopted to share bank risks, effectively enhance banks’ willingness to bear risks, and reasonably guide the flow of bank credit funds. In addition, we will further strengthen policy coordination and coherence, guide and stabilize market expectations, and take a combination of measures to expand effective investment.