With the rapid development of China's economy and society, population mobility has become increasingly frequent, and the scale of cross-regional medical treatment continues to expand. This presents new challenges for healthcare security, particularly in the supervision of cross-regional medical services. In the context of medical treatment received outside one's hometown, the supervision of medical insurance funds involves different regions and multiple departments, and it is necessary to form an effective collaborative regulatory force. Improving the coordination mechanism for medical insurance fund supervision is an effective means to address the difficulties in supervising medical treatment received outside one's hometown. Based on the theories of collaborative governance, principal-agent, and information sharing, this paper thoroughly analyzes the current difficulties in the coordinated supervision of medical insurance funds for medical treatment received outside one's hometown and proposes specific suggestions for establishing and improving the coordinated supervision mechanism of medical insurance funds.