During the operation of the utility boiler,the heat load distribution in the furnace of boiler is affected by a lot of factors,such as fuel types,combustion mode,furnace shape and so on.Usually,it is very difficult to accurately predict the heat load distribution in the furnace of boiler.This paper introduces a method for determining the heat load distribution in the direction of the width in the furnace of ultra-supercritical once-through boiler.Wall-tangentially combustion is the mian combustion mode of the boiler.The outlet temperature of the pipe under a certain operating condition is considered as a known condition.Combined with structural parameters of the boiler,hydrodynamic calculation of the water wall system is implemented.The pressure drop calculation model is established.The flow characteristics of the water wall system and the heat transfer characteristics of boiler furnace are studied.Then,the resistance,pressure drop and flow of the water wall can be easily determined.According to the results of the hydrodynamic calculation,the heat load distribution in the direction of the width of the water wall is obtained.Based on this calculation,the model of the heat load distribution is established.Then,another condition is calculated and analyzed under this model.The results show that the method for determining the heat load distribution proposed in this paper can accurately reflect the distribution of the total endotherm of each tube along the width of the furnace.The results of the paper can be applied to boiler safety analysis.