Based on the informal institutional perspective of regional cultural environment,this paper analyzes the influence of regional culture on accounting information quality and audit opinions by using the data of A-share listed companies in Shanghai and Shenzhen from 2005 to 2016. The results show that auditors from the high level of uncertainty avoidance areas tend to issue non-standard audit opinion, and auditors from the low level of uncertainty avoidance areas tend to issue standard audit opinion. Further research has found that the lower the level of uncertainty avoidance of regional culture, the lower the financial quality of the company, and the more inclined the auditors to issue non-standard audit opinions. Therefore,cultural environment is an important factor that affects the quality of accounting information and audit opinion, which can provide the empirical support for the information users to understand the auditor’s behavior from the perspective of culture.