<p>High temperatures significantly affect both the mechanical response of slab tracks and the properties of interface repair materials. In order to improve maintenance effectiveness, lower secondary damage and repair workload, an interface repaired model of CRTS III slab track with a temperature-dependent cohesive zone model (CZM) was presented. The secondary damage and mechanical response were calculated under various repair depths and glass transition temperatures (<i>T</i>_<i>g</i>) of repair materials. Results show that although the interface repair is effective under normal conditions, high temperatures significantly impact it, leading to secondary damage and interface stress mutations. During high-temperature summers, interface secondary damage gradually decreases from the slab side/end to the center. In high-geothermal tunnels, a similar pattern is observed in the slab corner, but the opposite occurs in the original-repaired interface transition zone. The mechanical response in both conditions shows a clear correlation with the repair depth. Based on theoretical analysis, field data, and structural requirements, an interface repair depth grading with lower workload is recommended: grade I for a depth of 50–100 mm (observation and recording), grade II for 100–150 mm (timely repair), and grade III for 150–170 mm (immediate repair).</p>