BeiDou satellite navigation system (BDS), which is expected to offer PNT service around the world in 2020, is currently in the stage of continuous launching and improving. In order to develop service capabilities, BDS carries the medium-altitude Earth orbit navigation satellite search and rescue (MEOSAR) payloads and global short message communication (GMSC) payloads on a part of MEO satellites. These payloads provide global MEOSAR service and GMSC service, while the GMSC payloads can also offer SAR service. The characteristics of SAR system based on BeiDou global navigation satellites, which is abbreviated as BDS SAR system can be analyzed by studying and comparing MEOSAR system with the SAR system based on GMSC, which is defined as GMSC SAR system. Benefitting from using the dedicated frequency allocated by ITU, the MEOSAR system can avoid the possible interference from other systems. Moreover, the completion of MEOSAR system construction will improve to establish an international image of Chinas responsibility for fulfilling humanitarian relief. While the GMSC SAR system also has some helpful merits to carry out rescue work smoothly, such as implementing ID identification which enable to obtain the identity information of the user directly, and realizing the short message communication which can be used to contact the distress users to report the location information, physical condition. Furthermore, owing to complete intellectual property and characterizing with independent and confidential, the GMSC SAR system is especially suitable for military use. Here come two development proposals of the BDS SAR system through analyzing the characteristics and current situation. First of all, the return link should be established as soon as possible. The other advice is to develop an integrated user terminal for both MEOSAR system and GMSC system.