The deep-sea green intelligent technology test vessel “WEI LAI” is designed primarily for tasks including the pilot testing of green intelligent technologies, surface support for deep-sea equipment, and comprehensive marine scientific surveys. It features a rational overall layout, strong retrofitting and reconfiguration capability, flexible equipment integration, excellent maneuverability, a high degree of intelligence, and powerful testing capabilities. It serves as a crucial cornerstone for supporting the intelligent upgrading and green development of key systems and equipment and for promoting the transformation and industrialization of scientific and technological achievements. This paper briefly describes the functional orientation of the "WEI LAI" vessel and analyzes its design requirements from the aspects of functional diversification, whole-vessel modularization, and system intelligence. It then presents the overall schemes for the ship type and general arrangement, modular retrofitting design, and key systems, including the power redundancy and hybrid propulsion system, intelligent information system, integrated platform for intelligent and dynamic testing, power system sea trial verification platform, dynamic testing system, and test collaborative control system. This paper can provide references for the development of special test vessels for marine equipment.