The invention discloses a urea solution automatic putting optimizing device and method for a circulating fluidized bed unit. The device comprises the circulating fluidized bed unit, a control module and an adjusting valve for adjusting the urea solution flow, and the circulating fluidized bed unit comprises a circulating fluidized bed boiler, a steam turbine and an electric generator which are sequentially connected. The method includes the steps that (1) the current loading value of the electric generator is obtained; (2) the urea solution putting quantity set value is obtained; (3) the ureasolution feedforward quantity is obtained; and (4) the urea solution adjusting valve opening degree is obtained. The device and method are reasonable in design and good in using effect, the compensation dosage of a urea solution needed by NOx concentration is considered, the difference value between the preset electric generator load target value and the electric generator actual load is used forcompensation correction of the urea solution putting quantity set value, the urea solution adjusting valve opening degree is obtained, control over the urea solution flow is achieved, and practicability is high.