The present invention provides method for operating a multipoint control system, which includes a plurality of controlled units serially connected and each controlled unit has a execution unit and an interpretive unit having a data processing unit and a memory unit, utilizes start packets pass through every one of controlled units which could be modified and transmitted to the next stage to achieve addressing for all of the system. Specifically, an information stream including a first start packet including a first leading message and a plurality of first data packets are transmitted by a controller, and a first address in the first start packet is modified by data processing unit and transmitted to the next stage. In addition, a first data packet corresponding to the first address is retrieved by the interpretive unit and the execution unit is enabled by the interpretive unit.