This paper analyzes the character and performance of the synthesized test bed on ground of small satellites. By studying several small satellite systems, the hardware and software architectures of flexible test bed are presented. The design ideas of the on-board part and the ground part of small satellite are given. The dynamic configuration for communication request/reply relation, the definition and resolution of the telemetry data signals are mainly discussed. The design and corresponding implementation are proven very effectively on the development of three small satellite systems.