Based on the “Immune System” theory and the provincial panel data of China Audit Yearbook from 2007 to 2014, this paper studies the logical correlation between state audit and financial fund security. The results show that disclosure function, resistance function and prevention function in “Immune System” of state audit can effectively play to prevent and resolve the operational risk of local financial funds, and improve the security of financial funds. However, the effect of state audit function is relevant to whether and how the auditees would rectify the issues identified by auditing offices. If the intensity of rectification efforts is great, the audit function will play an important role in the security of financial fund, otherwise, will be not obvious. Therefore, the audit work not only aims to discover potential problems of the auditee, but also urges the auditee to conduct timely rectification in accordance with laws and regulations, and ensure the effective supervision of the operation of the financial funds.