The invention discloses a desulfuration pulp circulating pump RB method and system. The method comprises the steps that a triggering condition of a desulfuration pulp circulating pump RB is set; when the triggering condition of the desulfuration pulp circulating pump RB is met, a unit coordination system is switched into a state that a furnace is followed by a machine from a state that the machine is followed by the furnace, a desulfuration accident spray device is started, the set target load and the load dropping rate of the desulfuration pulp circulating pump RB are set in a load loop of the unit coordination system, coal mills are disconnected according to the number of the running coal mills, the fuel value corresponding to the target load of the desulfuration pulp circulating pump RB serves as a fuel instruction to be sent to a boiler host, and therefore non-planed stopping of a unit is avoided. Due to the fact that the new desulfuration pulp circulating pump RB function is designed, synchronous, long-time and stable running is achieved between a desulfurizer and the boiler host, and the frequency of non-planed unit stopping caused by the full stop fault of a desulfuration pulp circulating pump is greatly reduced. The method and system have decisive significance in guaranteeing safe unit running and reducing the number of times of non-planed unit stopping, and play an important role in protecting safety of units on the power plant side and safety of power supplying on the power grid side.