As the "lifeline funds" safeguarding citizens' health rights, the secure and sustainable operation of medical insurance funds is directly tied to the fairness of the healthcare system and public well-being. Against the backdrop of accelerating medical insurance informatization and strengthened regulatory efforts, fraudulent insurance activities have exhibited new characteristics, including shifts in perpetrator roles, collusion in criminal chains, and technologically sophisticated methods, posing severe challenges to fund security. Through a study of publicly reported typical cases of medical insurance fraud in Jiangsu Province, this paper systematically analyzes the emerging internal logic of fraudulent behaviors, explores underlying causes such as institutional flaws and management gaps, and proposes a systematic governance framework from four dimensions of hub control, vulnerability mitigation, enhanced regulatory effectiveness, and long-term mechanism improvement. This framework follows a "incentive restructuring-technology empowerment-collaborative linkage-ecosystem optimization" approach, providing empirical reference and practical guidance for fortifying the security of medical insurance funds.