Abstract: In the field of offshore thermal insulation pipelines, HCFC-141b is widely used because of its low thermal conductivity and good compatibility with polyether polyols. Due to its ozone layer destruction and greenhouse effect, China will completely stop producing and using HCFC-141b by 2030 according to the Montreal Protocol. In view of the prefabricated rigid polyurethane foam spray offshore insulation pipe technology, considering the factors of environment, thermal insulation performance, safety and price, HFC-245fa blowing agent system is selected as an alternative plan. Through the analysis of compressive strength, the direction of formulation development is determined. Compressive strength evaluation, insulation layer test and on-site process verification are carried out to verify the adaptability of the developed formulation. The results show that the developed HFC-245fa blowing agent system is superior to the relevant standard requirement, and it meets the spray insulation technology and adopts to the application of offshore insulation pipeline.