中文摘要：

本文探讨审计委员会治理、避亏动机对上市公司年报审计意见类型以及不利审计意见改善和审计意见恶化的影响，考察审计委员会对公司管理层审计意见购买行为的治理作用。研究表明，设立审计委员会的上市公司年报被出具非标准审计意见的可能性更低，审计委员会独立性越高，上市公司年报被出具非标准审计意见和不利审计意见改善的可能性越低；在结合考虑避亏动机之后同样发现，审计委员会拥有双重的治理作用，在董事会中设立审计委员会并切实提高审计委员会的独立性和勤勉程度，不仅有助于提升上市公司财务报告的质量，而且亦有助于对拥有强烈避亏动机的管理层的审计意见购买行为进行较为有效的制衡。

英文摘要：

The paper discusses the impacts of audit committee governance and motivation of avoiding loss on the likelihood of receiving modified audit opinions, and of the improvement and deterioration of audit opinions and explores the governance effects of audit committee on audit opinion shopping of the management. Empirical analyses indicate that： （1） listed companies with audit committees have lower likelihood of receiving modified audit opinions than other listed companies; The independence of audit committee is significantly and negatively associated with the frequency of receiving modified audit opinions and the improvement of unfavorable audit opinions. （2） Audit committee has dual governance effect that the existence, independence and diligence degree of audit committee help to not only improve the quality of financial reports published by listed companies but also counterbalance behaviors of audit opinion shopping of the management, which has strong motivation of avoiding loss, after taking motivation of avoiding loss into consideration.