关键词: 双重机器学习, 银行竞争, 企业负债, 融资约束

Abstract: This paper takes the deregulation of bank branch entry barriers in 2009 as an external shock and explores how bank competition influences firms' debt and investment This paper uses double machine learning method to identify causal relation，which can solve the risk of misspecification in traditional OLS regressions as well as the regularization bias in machine learning The results indicate that intensifying competition in banking sectors not only significantly reduces the corporate financing costs，increases firms' financing ability of longterm debt，but also brings firms back to the real economy In addition，SMEs enjoy more benefits brought by this reform This paper is important for solving the financing problem of SMEs，improving the financialization of firms and optimizing financial resource allocation

Key words: double machine learning, bank competition, corporate debt, financial constraints