Foreign bank entry will not only alleviate corporate financing constraints, but also reduce the agent conflicts.Then how does foreign bank entry affect corporate investment efficiency? Based on the data of Shanghai and Shenzhen A-share listed companies in China from 2005 to 2015, this paper finds that foreign bank entry can significantly increase corporate investment efficiency, and this effect is more significant in large corporations, showing the obvious "cherry-picking" effect.Compared with state-owned enterprises, the effect of foreign bank entry on corporate investment efficiency is more significant in private companies, especially large private companies.Further study finds that, foreign bank entry overall improves corporate investment efficiency through the mitigation of financing constraints and the inhibition of agent conflicts, and the role in mitigating financing constraints is more significant.In addition, in private companies, foreign bank entry improves corporate investment efficiency mainly through the mitigation of financing constraints; in state-owned enterprises, foreign bank entry improves corporate investment efficiency mainly through the inhibition of agent conflicts.This paper not only supplements the relevant researches of factors affecting corporate investment efficiency, but also sheds light on how to guide foreign bank entry better and play its positive role better.