Abstract: The sodium-cooled fast reactor is one of the promising reactor types for the fourth generation of nuclear energy systems because it can improve the utilization of uranium resources and reduce the generation of nuclear waste. At the same time, sodium-cooled fast reactors have a more complex structure inside the reactor due to the use of metal wire winding to hold the fuel rods. In this paper, CFD software is used to model seven fuel rod bundles with winding wires for the core design of sodium-cooled fast reactors, and the turbulent mixing coefficients of winding wires are obtained based on the Reynolds stress of the flow field. Meanwhile, the same geometric model was established based on the self-developed sub-channel calculation program SAC-SUB（System Analysis Code-Subchannel model）, and the turbulent mixing coefficients were input into the sub-channel calculation program to obtain the temperature distributions of the interior channel, edge channel and corner channel, and the calculation results of the two software were compared. The comparison results show that for different channels, the temperature deviation of the interior channel is the smallest（2.5 ℃） and the temperature deviation of the corner channel is the largest（13.2 ℃） for the two calculation software. For different flow rates, the temperature deviation is smaller for the medium flow rate condition（condition 2）, with a minimum temperature difference of only 0.8 ℃. This work provides a technical basis for the selection of mixing coefficients for the subsequent fast stack sub-channel analysis.