Taking Chinese A+H share cross-listed firms from 2010 to 2018 as samples, this paper analyzes the impact of the voluntary dual audit on the cost of debt financing after the cancellation of the mandatory dual audit requirement. The main findings suggest that firms voluntarily using the dual audit have a lower cost of debt financing than firms dropping the dual audit. Further tests show that the effect of the voluntary dual audit on reducing the cost of debt is more pronounced in firms with lower information transparency; firms voluntarily using the dual audit obtain more debt financing than firms dropping the dual audit. The conclusions have enlightening significance for the internationalization of the local audit industry in the new era. In the context of promoting the domestic and international dual circulation, it becomes a necessary and urgent task to enhance mainland audit firms’ H-share audit service and brand image popularity and accelerate their acquisition of international recognition.