Purpose-The purpose of this paper is to study the capital structure of firms when controlling shareholders decide on the level of debt financing in an environment with poor legal protection.Design/methodology/approach-Theoretically this paper uses a dynamic model to analyze how the controlling shareholder expropriates the firm’s benefit through debt financing.Empirically this paper uses a sample of Chinese publicly listed firms from 2004 to 2007,through the method of OLS and panel data,to verify the theoretical predictions.Findings-Theoretically this paper finds that firms with controlling shareholders will take excess debt financing in an environment of controlled interest rate and poor legal protection to minority shareholders.Govment intervention exacerbates while controlling shareholder’s cash flow rights constrains excess debt finandng.The empirical results conclude that the improvement of the legal environment,limiting govment intervention,and raising controlling shareholder’s cash flow rights will effectively reduce excess debt level,as well as long-term debt ratio.Originality/value-First,this paper provides a theoretical model to explain the mechanism of how the ownership structure,legal environment and govment intervention interact to impact debt financing.This result also provides a theory to explain the paradox in a transitional economy that better legal protection lowers debt level and long-term debt ratio.Second,this paper provides further evidence on controlling shareholder’s expropriation to minority shareholder through debt financing.