<p>Gas turbine performance, crucial to modern energy systems, is significantly influenced by the quality of recuperator welding. Plate-fin recuperators are widely utilized owing to their excellent heat transfer capabilities. However, the multilayer structures of these recuperators are prone to thermally induced deformation and cracking during vacuum brazing. This study employs finite element simulation to analyze temperature field evolution and thermal stress distribution in multilayer plate-fin recuperator cores during vacuum brazing. Moreover, optimized process parameters are introduced to enhance brazing quality. The findings reveal that in both single-layer and multilayer cores, the outer regions near the heat source exhibit faster heating rates than the central regions. Maximum thermal stress is concentrated in the filler metal zones. A mathematical model (R² &gt; 0.99) is developed to correlate dwell time with layer count at four critical temperatures: 500 °C, 966 °C, 1080 °C (heating), and 700 °C (cooling). This model provides theoretical guidance for designing vacuum-brazed recuperator cores with arbitrary layer counts. This study extends vacuum brazing research from single-layer structures to complex cores exceeding ten layers. Optimizing temperature field uniformity and thermal stress distribution enhances welding quality and production efficiency. The findings provide strong technical support for advancing brazing processes in gas turbine recuperators.</p>