The research on the financialization of enterprises in the field of capital market and financial market is getting more in depth, but in the field of audit is lack of attention. This paper takes the A stock listed companies of China from 2010 to 2018 as the research sample, and empirically tests the influence of corporate financialization on audit quality and the regulating effect of internal control on the relationship between the two factors. It is found that there is a significant negative correlation between financialization and audit quality, and internal control can significantly inhibit the negative effect of financialization on audit quality. Firstly, further research shows that the complexity of audit business and audit risk play a significant intermediary effect in the role of enterprise finance on audit quality while enterprise financialization will damage audit quality by increasing business complexity and audit risk. Secondly, the auditors from the four major accounting firms have stronger professional competence and independence, and after continuous audit, they can make better use of internal control to deal with the risk of financialization of enterprises; And finally, in a deeper understanding of the mechanism of internal control, internal supervision in the five elements of internal control significantly suppress the negative effect of financialization on audit quality, while internal environment, risk assessment, information communication and control activities fail to achieve such a result. It stands the reason that the research will enrich the relevant researches in the field of enterprise financialization and audit quality, expand the theoretical boundary of financial economic consequences, and also provide empirical evidence for establishing and improving a sound internal control system.