The initial sample of this paper includes listed firms with overdue loans between 2001 and 2016. From the perspective of whether the auditors delay to disclose the modified audit opinions, the paper explores audit quality in a brand new way. The results indicate that: Compared with the previous year when the company publicly defaulted on overdue loans, auditors are more inclined to issue modified audit opinions and indicate the overdue risk information just in the overdue year, exhibiting apparently the auditors’ delayed disclosure. This phenomenon only significantly exists when the information content of overdue loan risk is relatively high. After the implementation of the 2006 bankruptcy law, auditors significantly reduce their delayed disclosure behavior. The findings above suggest that: When the legal risks are low and the auditing standards are relative fuzzy, the auditors haven’t disclosed clients’ default risks, which reduce the content of audit report and is a reflection of low audit quality