In sodium-cooled fast reactors, the flow rate distribution of coolant is not uniform in the reactor core, resulting in temperature differences of coolant in different subchannels. The wrapped wires of fuel rods enhance the mixing of coolant, and when the convection of coolant with different temperatures occurs between neighboring subchannels, it will lead to the thermal striping phenomenon of the surrounding fuel rods, resulting in the thermal fatigue damage of the fuel rod structure. Aiming at the thermal striping phenomenon of wire-wrapped fuel rods, a CFD model containing seven fuel rods is constructed, and the LES turbulence model is selected for transient calculation. The temperature and pressure fields obtained from the CFD simulation are unidirectionally transferred to the finite element model of the fuel rods for transient calculation, and the simulation results are compared with the results calculated by the theoretical formulation of thermal striping. The results of the study are as follows: (1) There is obvious thermal striping in the flow field between neighboring subchannels and the surrounding structures; (2) As the height increases, the temperature difference between the coolants in neighboring subchannels increases and thermal striping becomes more obvious; (3) Through the comparison of thermal striping at different thicknesses of the fuel rod cladding, the attenuation characteristics of thermal striping are obtained when penetrating deep into the internal structure. This paper is an in-depth study of the thermal striping phenomenon of wire-wrapped fuel rods for sodium-cooled fast reactors, and the results of the study can be used as a reference for the structural design of reactors.