Abstract: Abstract：[Objectives] Hydrogen-electric hybrid ships have zero emissions during the navigation process and take into account long endurance and load fluctuation adaptability, with excellent prospects. However, hydrogen produces carbon emissions in the production, transportation and storage, so it is necessary to carry out the life cycle carbon emission assessment of hydrogen-electric hybrid ships to comprehensively evaluate their carbon emission reduction capacity. [Methods] Firstly, the energy flow model of the power system is established on the MATLAB/Simulink software platform. ?Then, considering the life cycle of the power system, the carbon emissions of the life cycle under actual operating conditions are calculated. Finally, sensitivity analysis is performed on the calculation results. [Results] The results of an inland river ferry show that compared with the traditional diesel engine power system, the life cycle carbon reduction advantage of the hydrogen-electric hybrid system is significant. Meanwhile, the carbon emissions of the life cycle of the hydrogen-electric hybrid system are not necessarily lower than those of the traditional diesel power system, and due to the influence of hydrogen production, excessive hydrogen carbon emission intensity will lead to carbon emissions exceeding that of the diesel engine power system. [Conclusions] Based on energy flow model, this study provides a life-cycle carbon emission evaluation method with engineering significance.