Abstract: Determining the samples’ neutron flux distribution precisely in the irradiation channel is the base of irradiation experiment design. The sensitivity of some important factors affecting irradiation channels’ neutron flux in the High Flux Engineering Test Reactor（HFETR）is analyzed in the paper. The results of calculation and analysis show that the extent of the influence among the irradiation channels decreases with the channels’ distance increasing, the influence of the nearest channel can reach 8%. The samples’ neutron flux considering all burnup steps is more accurate than that of the middle burnup step, the deviation decreases as the irradiation flux increases, the maximum deviation is about 6%. The fast neutron fluxes are calculated respectively, considering axial burnup of the fuel elements around the irradiation channel are uniform distribution and cosine distribution, the deviation is about 4%, the calculation accuracy has been improved about 45%. Setting the height of the tally cells as 1.5～2.5 cm is available, considering the calculation efficiency and accuracy.