To study the thermodynamic performance limit of two-heat-source combined cycle, an ideal thermodynamic model of two thermal medium heat-work conversion system was constructed. The concept of exergy-driven thermodynamic process (EDTP) was proposed and classified by analyzing the process power relationship between the heat engine region and the heat pump region. Quantitative analysis was performed through the proportion of output power. The parallel flow and counter flow EDTP functions were constructed and solved. The thermal characteristics and thermodynamic performance limits of different types of EDTP under ideal conditions were analyzed. Results showed that the maximum process work of the parallel flow EDTP was greater than that of the counter flow EDTP, and the temperature crossover trend between the exothermic medium and the endothermic medium of the parallel flow EDTP was more obvious. The equivalent temperature rise in the endothermic medium could be used to determine the type of EDTP, and its maximum value could characterize the limit of output power. The evaluation of actual system showed that the total heat exchange of the series-type cogeneration system was 1.97 times that of the basic organic Rankine cycle (ORC), which is more suitable for occasions with simultaneous thermoelectric demand. However, the net output power efficiency (6.55%), exergy efficiency (26.61%), and thermodynamic perfectibility (36.38%) were significantly lower compared with the basic ORC. The method to improve the thermal performance of the two-heat-source combined cycle is worthy of study. This research can provide theoretical guidance for the thermodynamic performance limit and evaluation of different types of two thermal medium heat-work conversion systems.