Abstract: A NaOH solution was proposed to absorb CO₂ from ship exhaust gas for the reduction of marine CO₂ emission and achievement of green shipping.Firstly,CO₂ absorption principle with NaOH solution was conducted and a mathematical model of absorption efficiency was deduced.After installing the newly designed CO₂ absorption device on the 6135G128ZCa marine diesel engine,the factors,such as NaOH solution concentration and reaction temperature,were analyzed for influence on the CO₂ absorption efficiency.Results indicate that ship's CO₂ emission can be reduced over 20% after using NaOH solution under the full load conditions of the diesel engine.The results lay a foundation for the future study of marine emission decarburization technology.