Abstract: After the implementation of ultra-low emissions on coal-fired boilers,the distribution of the boiler tail flow field is more complicated and changeable.In order to improve the control system quality,it is necessary to improve the measurement accuracy.Kriging was applied to analyze the distribution of boiler flue flow.The denitrification inlet flue of 660 MW coal-fired unit was taken as an example.The variation function was performed to analyze the structural analysis.The simulation results are exponential model features,and the nugget sill ratio indicating spatial correlation is less than 25%,which proves that the region has good spatial correlation and is suitable for the Kriging method.After optimization,based on the values of 1/3 or less grid-method-sample,the distribution of NOx in the unknown region of the denitration reactor was calculated by Kriging method.The error between measured value and grid method is less than 10%,and the mean deviation of the nitrogen oxides concentration in the measured section is-1.67%,which satisfies the fowl mass balance requirement.The Kriging method provides a new flue test method.Based on a small number of measured points,it can calculate and analyze the whole flue distribution,and the error between the calculated value and the grid method is less than 15%.The Kriging method improves the accuracy of flow field test,and provides more accurate control parameters for the control system.