The invention discloses a quick load change control method of a subcritical circulating fluidized bed boiler unit. The control method respectively processes an AGC load instruction, a main steam pressure deviation signal, a steam turbine energy demand signal and a deviation between the steam turbine energy demand signal and a boiler advanced energy signal to obtain four corresponding control sub signals; the four control sub signals are summed to output to a boiler main controller; and the quick load change operation of the boiler unit is controlled according to the output of the boiler main controller. The method can improve the adjusting quality of the unit, the quick load change capacity of the unit and the capacity of adapting to the unit load response.