Abstract: A control system and a control method are provided. The method includes: controlling, by a primary host, a plurality of clients actively; coupling a secondary host to the primary host through a synchronization link and a transmission link different from the synchronization link, where the plurality of client are coupled to each other in series on the transmission link; transmitting, by the primary host, a first instruction to the transmission link, and transmitting a first synchronization signal corresponding to the first instruction to the secondary host through the synchronization link; and determining, by the secondary host according to the first instruction and the first synchronization signal, that a failure occurs on at least one of the synchronization link and the transmission link.