中文摘要：

本文探讨投资者保护条款的完善与执行、客户重要性与审计质量之间的关系,利用我国证券市场2003~2005年的数据研究发现：（1）客户重要性对审计质量并没有产生负面影响,事务所审计质量普遍有所提高;（2）随着法律责任的加重,法律保护条款的完善与盈余管理空间显著负相关,然而法律执行越严的省区,上市公司的盈余管理却越强烈,这表明中国证券市场出现了法律条款的完善与执行逆向起作用的＂背驰效应＂;（3）审计师对盈余管理方向的关注与国外文献的发现不一致,审计师能够关注重要客户操纵盈余减少的行为,但却无法控制重要客户操纵盈余增加的行为;（4）相对于规模较小的事务所而言,投资者保护条款的完善对规模较大的事务所提高审计质量具有更明显的促进作用。

英文摘要：

This paper discusses the relation of investor protection rules and its implementation,client importance and audit quality after the beginning of audit civil liabilities.Using a sample of listed A-share companies in China stock markets from 2003 to 2005,we obtain the following findings after controlling for relevant influential factors： Firstly,client importance hasn＇t affect negatively audit quality.Audit quality significantly improves.Secondly,with more legal liability,there is negative relation between the improvement of investors protection rules and earnings management.However,the listed companies located the province with stricter law enforcement have more earnings management.This indicated that there is ＇runs counter＇ effect on earnings management between the improvement of law rules and its enforcement in Chinese stock market.Thirdly,auditors take more attention on the negative earnings management that is different from the foreign research findings.Auditors can restrict negative earnings management but not positive earnings management.Fourthly,comparatively to the smaller audit firms,but the improving of investor protection rules significantly improves audit quality of the larger audit firms.