Abstract: The thermoelectric conversion system exhibits rapid transient response characteristics and operational temperature non-uniformity. Through structural and operational principle analysis, a transient multi-module modeling method incorporating temperature non-uniformity was developed based on the finite volume method. The system was discretized into computational units following heat transfer processes, with heat resistance employed to characterize thermal transport. Transient energy transfer equations were established based on energy conservation within each computational unit, comprehensively considering temperature inhomogeneity, device physical parameters, and related influencing factors. Prototype bench experiments under identical conditions validated the model through a comparative analysis of temperature, output power, current, and voltage, confirming error margins within acceptable limits. A model-based analysis further reveals that: high-temperature gas exerts a dominant influence on device hot-end temperature; cooling water temperature most significantly affects output power; load adjustment alters hot-end temperature, with maximum power achieved at a load ratio of 1.1.