Abstract: The object controllers in train control system are the important ground equipment in the next generation of train control system. They are the execution units of trackside signal equipment which control the signal equipment switching and transforming, meanwhile, undertake the task of executing command information and getting status of signal device. The correction of the data transmission plays an important role in the safe operation of trains. Aiming at the characteristics of distributed object controller in the next generation of train control system and its demand, this paper proposed a design method of communication subsystem for distributed object controller, verified the designed communication bus. Experimental result shows that the communication delay of the designed communication bus can be less than 20 ms which meets the communication requirements.