The thermal-management system of a new energy vehicle is a key to ensuring thermal safety and comfort. Battery thermal management and cabin cooling are strongly coupled, resulting in poor dynamic characteristics. Thus, this study examined a transcritical CO₂ vehicle thermal-management system, built an Amesim model of a thermal-management system and control system based on the co-control of thermal comfort and battery temperature, and analyzed the thermal-management system under different scenarios and conditions. It was demonstrated that the thermal-management system was able to quickly achieve a comfortable thermal environment of the cabin and ensure a suitable battery temperature under various conditions, with less fluctuation, prompt response, and excellent anti-disturbance performance. Compared to the traditional control method based on cabin temperature, this method could provide excellent cabin thermal comfort at all times, which verified the superiority of a thermal-management system based on this control method.