之前的审计学文献大多采用两分法将会计师事务所分为"N大"与 "非N大"两种类型，而后观察两类事务所在审计行为上是否有显著差异。这样做忽略了事务所国际化程度对审计行为的作用，也模糊化了事务所的规模效应。从国际化程度来看，中国的会计师事务所现业已形成"四大"合作所、国际会计公司加盟所和其他会计师事务所三种类型。国际会计公司加盟所无论是数量占比还是审计市场份额均超高40%，成为中国审计市场的一股重要力量。为此，本课题从加盟国际会计公司给会计师事务所自身带来的经济效果、给客户企业带来的溢出经济效应以及加盟方式与加盟对象选择带来的经济效果差异三方面分析中国会计师事务所加盟国际会计公司行为。本课题在学术上有助于理解事务所国际化行为对审计行为的作用，有助于理解新兴市场会计师事务所的成长路径选择，有助于理解第二或第三梯队国际会计公司的经济价值；在实践上有助于优化中国会计师事务所国际化行为的选择。

Prior studies classify auditors into "Big N" and "non-Big N" and then analyze their difference in auditing behaviors. This dichotomal method overlooks the role of auditor internationalization and also blurs the size effect. Considering the internationalization degree, there are three types of auditors in China: cooperative auditors of Big Four，member auditors of international accounting firms, and other local auditors. Member auditors now are important component of Chinese auditing market: both the number and the market share are above 40%. This project analyzes the behavior of joining international accounting firms by examining the economic consequences of joining for the auditors, the spillover effects of joining for client firms, and the moderating effects of joining method and joining objects. The results will contribute to academic research about the role of auditor internationalization in auditing behaviors, about the growth of auditors in emerging markets, and about the economic value of the second-tier and third-tier accounting firms. Practically, this research will help to optimize the internationalization choices for Chinese local auditors.