The invention discloses a circulating fluid bed unit anti-dry burning and water level adjusting device and a control method therefor. The device comprises a condenser, a steam seal cooler, a slag cooler, a low-temperature coal economizer, a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a deaerator, wherein the condenser is arranged at the starting end ofa condensed water pipeline, the deaerator is arranged at the tail end of the condensed water pipeline, and the steam seal cooler, the slag cooler, the low-temperature coal economizer, the first low-pressure heater, the second low-pressure heater, and the third low-pressure heater are sequentially arranged on the condensed water pipeline. A condensed water recycling pipeline is arranged behind thefirst low-pressure heater, and the pipeline is a system pipeline for preventing dry burning of the slag cooler; a pipeline to the condenser is arranged on a backwater pipeline behind the slag cooler,and the pipeline is a system pipeline for deaerator water level adjusting; and according to the device, the water level of the deaerator can be adjusted, cooling water for the slag cooler of a circulating fluid bed can also be provided so that the circulating fluid bed can stably operate even under the working conditions with condensed water.