Objective The biomechanical model for the musculoskeletal system of a human knee joint was established using a numerical simulation method. The kinematic and dynamic information captured during jumping motion simulated by the human dynamic model was used as driven data of the knee biomechanical model, followed by further analysis of the stress field distribution characteristics of the meniscus under different thermal-force coupling knee brace conditions. Methods Based on computed tomography and magnetic resonance imaging of the subject, a realistic human knee model, including bone, articular cartilage, meniscus, ligaments and peripheral soft tissues of the knee joint, was constructed. Furthermore, two gaits, namely taking-off and landing-on, of jumping motion with an increased risk of meniscus injuries were selected according to mechanical features in full-cycle jumping motion. Subsequently, the stress field characteristics of the knee meniscus under four different thermal-force coupling knee braces were analyzed, the changes of the peak stress of the meniscus and its stress concentration area were discussed, and the protective efficacy and mechanical basis of meniscal injuries and wearing knee braces were explored. Results The anterior part of the medial knee meniscus was a vulnerable area under concentrated stress. Under the knee brace thermal-force coupling condition, the stress concentration area of the medial meniscus was transferred from its narrow and weak anterior part to its wide and thick middle part, and the peak stress was also significantly reduced. The peak stress on the medial meniscus and that on the lateral meniscus were similar, indicating that the two parts of the meniscus bore the external load evenly, and the meniscus stress concentration area decreased. Conclusions Thermal-force coupling knee braces have good protective effects against knee meniscus injury. The numerical simulation provides theoretical support and technical guidance for the design of multifunctional thermal knee braces.