A study on the development of spacecraft attitude control system using a 3 axis spacecraft attitude control ground testbed is discussed in this paper. The testbed structure is made of aluminum structure width a configuration for general satellites. The testbed is connected to an air bearing for the 3 axis attitude control and some panels are located in the testbed holding experimental equipments. Experimental equipments are connected by wires to transfer power and signal. An OBC(On Board Computer) is used as a controller with on-board signal processing software developed. RF modems are installed between the testbed and a PC used as a ground station. Telemetry & command data processing software is also designed.