This paper firstly summarizes the accounting information system and audit, and then discusses the types and causes of audit risks, including the risks of the system itself, auditors, internal control, etc., and analyzes the reasons from the perspectives of technology, personnel quality, physical security and data protection. Finally, four effective strategies to avoid risks, namely strengthening internal control, attaching importance to external audit, building security guarantee mechanism and improving the quality of auditors, are put forward to provide reference for reducing the audit risk of accounting information system.