The concept of green design is widely used in industrial products and architectural design,but the application experience is less in sea reclamation engineering.Colombo port city project is a large artificial island reclamation project,which locates in Sri Lanka,the key node country of “the Belt and the Road”.We apply the green design idea of safe,energy-saving and ecological as guideline,fully combine with environmental assessment and engineering research to determine the location selection,overall layout,canal layout optimization,and adopt low and narrow crest type of breakwater through functional requirements analysis.According to the actual sit situation,we conduct design changes in time to achieve the destination of save economy and environmental protection.The detailed environmental monitoring during the construction period proves that the effect of green design has reached the expected level and achieved good environmental benefits and social effects.