For large-scale reclamation projects，the closure earthwork of the land boundary is an important design content to ensure stable penetration of the embankment and isolate internal and external water systems to meet high environmental protection requirements. However，the traditional closure earthwork by grabbing mudflats and backfilling in layers has the characteristics of low construction efficiency，weak soil strength，and difficulty to use land in closure earthwork areas，which often become a key issue that restricts the progress of the project. Based on the design and construction of the closure earthwork of the Zhoushan Green Petrochemical Base Reclamation Project，we have realized large-scale closure earthwork fast backfilling and hardening through the application of soil solidification technology. At the same time，combined with engineering practice，we summarize the main points of the application of the key technical issues when solidified soil is used as closure earthwork and the existing problems.