Considering the requirements of global coverage and link resource occupation in Telemetry, Track and Command (TT&C) system for Low Earth Orbit (LEO) satellite, this paper analyzes the basic capability of Global Short Message Communication (GSMC) in the BeiDou Navigation Satellite System (BDS-3) used in LEO satellites TT&C system. Besides, the system composition, work process and functions of using GSMC in BDS-3 are described, and relevant key technologies for TT&C system management are classified as well. This paper also includes some preliminary solutions to these key technologies and also provides suggestions for the application modes in TT&C system.