Abstract: To provide integrated communication-navigation means for maritime distress and safety communication, China has established the BDMSS（BeiDou Message Service System） based on the BeiDou system′s regional short message capability. After five years of operation, BDMSS has been successfully recognized by the IMO（International Maritime Organization） as a GMDSS（Global Maritime Distress and Safety System） service provider. This paper outlines the evaluation and recognition procedures for mobile satellite systems used in GMDSS, as defined by the IMO and the IMSO（International Mobile Satellite Organization）. It examines BDMSS′s application process for IMO recognition and the technical and operational assessment conducted by IMSO. Key assessment points for BDMSS, including availability, restoration and spare satellite arrangements, priority mode, on-site demonstration scenario design, and additional considerations, are analyzed. The results enhance understanding of the international approval and evaluation criteria for potential GMDSS mobile satellite systems. Furthermore, they provide valuable references for future revisions of IMO Resolution A.1001（25） and for incorporating international maritime requirements into the design of new mobile satellite systems.