Abstract: In view of the inherent delay of boiler heat signal in boiler combustion monitoring and the characteristic that combustion radiant energy signal in boiler can reflect combustion load change in time,an on-line monitoring system for combustion radiant energy in boiler based on the technology of radiometric image processing and spectroscopic analysis was developed.A flame image detector was designed to acquire the radiation image of the furnace,combined with a spectrometer to calibrate the radiation image of the furnace online,and online monitoring software for the combustion temperature distribution and radiative energy signal of the furnace was developed to capture the thermal radiation image of the combustion in the furnace in real time,and to obtain the combustion temperature distribution as well as the radiative energy signal of the furnace.The on-line monitoring application on a 330 MW coal-fired power unit was carried out,and the comparison with the actual power of the unit was analyzed.The results show that the radiative energy signals obtained by the system from the combustion in the furnace can react in time or even ahead of the combustion load changes in the furnace,no matter in stable or variable load conditions.