对于审计师质量与资本结构之间的关系，现有实证研究并不充分，而在理论上，对于这两者之间的关系存在不同的预测。本文利用我国2008-2011年A股上市公司及其主审会计师事务所数据，以行业专长和规模作为审计师质量的替代变量，实证考察我国上市公司基本完成股权分置改革这一背景之下审计师质量对资本结构的影响。结果发现，如果不考虑审计师质量与资本结构之间的相互影响，审计师质量对资本结构没有显著影响；而在考虑这两者之间可能存在相互影响并采用联立方程方法来解决这一内生性问题后，审计师质量对资本结构具有显著的负向影响。进一步研究表明，上述负向关系在国有企业中要比在非国有企业中更为明显。此外，上述负向关系存在于法治环境、信贷环境较好地区，而在法制环境或信贷环境较差的地区，并不显著。

There are different theories about the relationship between auditor quality and capital structure, and relevant empirical researches are very limited. Using the data of A share listed companies and their auditors from 2008 to 2011, this paper investigates the effect of auditor quality (proxied by industry expertise and scale of audit firm) on capital structure. The results show that there’s no significant association between auditor quality and leverage when single equation is used. The single equation method is inappropriate, however, auditor quality and leverage may interact with each other in theory and the result of Hausman test confirms the simultaneity between the equation of auditor choice and that of the determinants of leverage. Then, simultaneous equation approach is used to deal with the problem of endogeneity. The results under simultaneous equation approach demonstrate significant negative effect of auditor quality on leverage. Further tests show that such negative effect is more profound in state-owned companies or companies located in the districts where the legal institution environments or credit environments are good.