As an important means of non-penalty regulation of the capital market， the Exchange's inquiry mainly focuses on the risk sensitive events of listed companies and has rich information content. Under the risk-based auditing model， does the auditor consider the exchange inquiry supervision as a risk signal when making pricing decisions? Taking the Shanghai-Shenzhen A-share listed companies between 2015 and 2017 as a sample， we first explore the impact of exchange inquiry regulation on audit fee. The study found that the listed companies receiving the exchange inquiry letter will have a significantly higher audit fee in the current year than the companies that did not receive the inquiry letter. Further research found that when a listed company is frequently questioned for a period of time， the auditor will charge a higher audit fee； in particular， when the inquiry letter related to the accounting information， the increase in the audit fee is more significant..