Abstract: Aiming at the influence of the brazing connection layer in the thermoelectric refrigeration module on the stress field of the module, taking the C-31107 thermoelectric refrigeration module as the object, this paper establishes a thermo-electric-structural coupling multi-physics model composed of 31 pairs of thermocouples. Then this paper adopts the finite element numerical simulation method, introduces the Anand modified constitutive equation describing the viscoplastic material, establishes a thermoelectric model with a solder layer, and compares it with a thermoelectric model without a solder layer under different working conditions. And the influences of the cross-section size and thickness of the solder layer on the temperature field and mechanical properties are analyzed. In the presence of the filler metal layer, the maximum von Mises stress of thermoelectric legs is reduced by at least 20.41% and 31.34%when the current is 2.4 A and 2.6 A, respectively. It indicates that the filler metal layer can connect the metal and relieve stress. The optimal solder layer geometric parameters are determined, i.e., the cross-section length is 0.975 mm~1.025 mm, the hot side thickness is 0.0825 mm~0.085 mm, and the cold side thickness is 0.095 mm~0.100 mm. Therefore, the solder layer plays a vital role in thermoelectric module design and application research.