Currently, TTC （Tracking, Telemetry and Command） for satellites of our country is mainly executed by Ground-Based TTC network. With the increment of requirement for different kinds of purposes, the numbers of satellites in lower orbits increase rapidly. It is very difficult to meet the requirements of the satellites only based on ground-based TTC network. To seek a new, effective and economical mode to TTC lower orbit satellites is absolutely necessary for our country and to apply space-based TTC technology is an appropriate way to solve ground-based equipment shortages. Based on analysis of Tracking and Data Relay Satellite System （TDRSS） of NASA （National Aeronautics and Space Administration of the United States）, a new mode, space-ground-based TTC Mode （SGBM） for lower orbit satellites, is proposed. In this paper, the operating principle of space-ground-based TTC mode is discussed, the simulation system used to simulate space-ground-based TTC mode is designed, and the key technologies need to be solved when using space-ground-based TTC mode is analyzed. The different functions of space-ground-based TTC mode are verified based on the developed simulation system. The simulation results show that the proposed satellite TTC mode is feasible and reliable, and the requirement of lower orbit satellite can be met by using the mode.