Abstract: UAS operational identification is a foundational technology for digital supervision of low-altitude airspace, providing critical support for aircraft identity verification, flight status tracking, and violation accountability. First, this paper elaborates the technical principles of the two core modes—broadcast-based and network-based operational identification. Second, it reviews the international evolution of this technology from early conceptual exploration to standardized engineering application, with an in-depth interpretation of the international standard system comprising ASTM F3411, ASTM F3586, and ASD-STAN EN 4709-002. Third, it analyzes the development pathway of UAS operational identification in China from enterprise-led exploration to the issuance of the national mandatory standard GB 46750-2025, focusing on its technical requirements and removal-invalidated anti-tamper mechanism. On this basis, key limitations of existing systems are identified, notably channel congestion in high-density airspace and constrained onboard computing capacity. In summary, UAS operational identification has evolved from a compliance-enabling mechanism to a foundational capability for low-altitude autonomous operations. Future research should address channel access contention mitigation, lightweight cryptographic authentication, and the integration of multi-UAV cooperative collision avoidance, while ensuring data security and privacy.