In order to make the TT&C service more effective and convenient, and solve the problem of satellite TT&C resources shortage. The ability of using Tiantong satellites to support LEO TT&C is researched in this paper. As a GEO mobile communication satellite system, there are many advantages on Tiantong TT&C，such as the real-time transmission, reliable service, and low costing. We analyzed the service capabilities of Tiantong satellites for different LEO orbits. Besides LEO satellites, the space station and rocket are also considered in this paper. In order to support the space-based TT&C, the modification solution and detailed work flow are introduced based on the existing structure of Tiantong satellite mobile communication system. Finally, combined with the current technology development trend and Tiantong satellite capabilities, the application scene of space-based TT&C and low rate data relay is described.