The Space-Based Space Surveillance (SBSS) system is an important way and the development tendency of accepting state information of space objects. However，only utilizing the measure information between the satellites would produce the deficient–rank phenomena in the process of orbit determination of space objects. The essence of deficient-rank problem in the autonomous orbit determination was discussed. The problem can be eliminated by the combined orbit determination strategy based on space/ground-based tracking telemetry and command technology. The tracking network was made up of 4 high-orbit surveillance platforms and 2 ground surveillance stations. The orbit determination function of the system for the space objects was simulated. Simulation experiment shows the orbit determination precision for three kinds of space objects based on the combined orbit determination strategy reaches kilometer level.