Abstract: Background and Objective: The shipping industry contributes for about 2.2% of the worlds total emissions. It is expected to continue rising by 50-250% by 2050, depending on future economic growth and energy development. Therefore, efforts are needed to reduce the amount of emissions issued by ships. There are many methods that can be used in order to reduce the level of ship emissions, one of which is decrease the speed of the ship. By lowering the speed of the vessel, it is expected that fuel consumption and ship emissions are also reduced. Methodology: This review paper focused the effect of ship speed on ship emissions, as well as highlighted the most common and effective methods recommended for reducing ship emissions. Results: In this study the relationship between ship speed and ship emissions were discussed. The past research was also discussed about the several methods of reducing the ships emission levels in terms of operations and the effect of speed on ship emissions. Conclusion: Research on speed optimization is mostly conducted for tankers and container types. For future studies it is expected that more speed optimization research with ship objects other than tankers and containers, such as LNG vessels or other fast vessels so that more renewal can be reviewed in it.