With the increasingly stringent requirements of marine environmental protection, all major classification societies have proposed their own environmental protection class notations. Among them, the additional class notation of DNVGL CLEAN（DESIGN）additional notation sets requirements for the design, operation and equipment of ships to reduce the ship's environmental impact from air emissions, sea discharges and hazardous materials from ship to shore. The environmental notation CLEAN（DESIGN）is quite stringent in the DNVGL rules, which is rarely used in the design of container vessels in recent years. A dual-fuel container vessel is a green ship that has the notation CLEAN（DESIGN）. In the process of research and development, the container vessel has broken through a series of design essentials, such as the arrangement of engine room and liquid tanks, sewage treatment and fuel tank protection, reaching a new level of green environmental protection for container vessels. This article systematically summarizes the requirements of CLEAN（DESIGN）notation for the machinery design of container vessels, and studies the influence of this notation on the machinery design of container vessels. It also shows the design ideas and schemes of this vessel combining with the practical project, and presents measures for further improvement of the environmental protection level of container vessels.