The insertable steel cylinder island construction technology is an advanced artificial island construction scheme with a short construction period and minimal environmental impact. To clarify the carbon emission characteristics of this technology and provide the guidance for the low-carbon construction of similar projects in the future, a carbon emission accounting method for the construction period of artificial islands was established based on the bill of quantities, and this method was applied to the east and west artificial islands of the Hong Kong-Zhuhai-Macao Bridge. The results show that construction-phase emissions are predominantly concentrated in the land formation, ground treatment, and island retaining structure stages, with both islands exhibiting similar emission profiles. At the process level, carbon emissions are highly concentrated, with nearly 30% coming from “the production and transportation of steel cylinder”. From the composition of sources, steel, concrete, and mechanical energy consumption are the main emission sources, accounting for approximately 38%, 23%, and 27% respectively. Finally, under the premise of considering feasibility, preliminary green carbon reduction recommendations were proposed for key emission sources such as steel, concrete, and diesel.