The dispersion of bank loans for enterprises has a double-edged sword effect in exerting debt supervision. This article explores the relationship between the diversification of corporate bank loans and audit fees from the perspective of independent third-party auditors, using data from A-share listed companies from 2016 to 2022. Research has found that the dispersion of bank loans for enterprises significantly increases audit fees, and this result is more significant in non-state-owned enterprises, banks without collateral requirements, lending banks that do not include foreign banks, and auditors with more professional experience and industry expertise. The mechanism test results indicate that the audit risks caused by the free riding of creditor banks when corporate bank loans are dispersed is an important reason for auditors to increase audit fees. In addition, auditors will further disclose more detailed key audit matters to address the audit risks of high loan diversification enterprises. This article expands the research perspective on the economic consequences of bank debt supervision, enriches the relevant literature on factors determining audit fees and auditor risk response strategies, and has important theoretical and practical significance for risk assessment and decision-making of stakeholders in the capital market.