In order to meet the increasingly stringent emissions restriction , it is indispensable to improve the combustion and emissions of high-speed marine diesel engines. Oxygen-enriched combustion and intake air humidification are effective way to controlling pollution and improving combustion for diesel engines. In this study ,the combustion and emission characteristics of supercharged intercooled marine diesel engine with humidification rate and intake oxygen concentration were investigated by using multi-dimensional CFD model．The combustion model was established by AVL Fire code. The combination strategy of intake air humidification and oxygen - enriched combustion was optimized under partial load at 1350 r / min. The simulation results indicate that under the constant amount of the humidification rate, the averaged cylinder temperature and pressure both increased with the rise of intake oxygen concentration, while the moment of the in-cylinder peak temperature and pressure happened in advance, the combustion heat release rate increased, the ignition delay and the combustion duration got short. At the same time, the emissions of Soot were inhibited, but the NO emission increased remarkably. Intake air humidification can reduce NOx emission effectively, whereas has little effect on Soot emission and brake specific fuel consumption. As the humidification rate increases，both of combustion pressure and temperature decrease，NOx emissions are kept decreasing．However，The ignition delay increased dramatic, and the in-cylinder burning deteriorated. Using the mixture, which blended oxygen-enriched air with intake air humidification, Smoke was reduced and excessive growth of NOx was inhibited, engine’s thermal efficiency and power should not be affected simultaneously.