<p>The increasing strictness of environmental regulations in the maritime industry has significantly promoted the demand for energy conservation and emission reduction in global shipping. Accordingly, the development of energy management systems with improved functionality, performance, and operational safety has become increasingly important. In this study, a hybrid powertrain energy management testbed based on an NI PXI real-time system is developed for system-level verification. The proposed platform integrates both energy management and fault-handling strategies, and is constructed through coordinated hardware–software co-design in accordance with the operational characteristics of a marine gas–electric hybrid propulsion system. Experimental results demonstrate that the proposed testbed can effectively reproduce realistic operating conditions of marine hybrid propulsion systems and reliably support system-level performance evaluation. Overall, the developed platform provides a scalable and practical validation framework for the development and application of marine hybrid power energy management technologies.</p>