Abstract:With the increasing capacity of generating units and the increasing level of automation,the importance of distributed control system (DCS) has become increasingly prominent.Aiming at the abnormal fluctuation of DCS system controller's load rate in a power plant,this paper analyses reasons among the hardware configuration,controller load distribution,processing cycle and logical configuration.And through checking and verification,it is confirmed that the reason of load rate fluctuation is the frequent occurrence of fault alarm signal of a card.In the end,the paper puts forward some preventive measures to deal with these problems,which can be used for reference in the management and maintenance of DCS system controllers.