Abstract: Polyurethane composite coating system is composed of combined polyurethane with special features and various hollow microspheres.With thermal insulation and protection functions, it can be divided into the organic hollow polymer composite polyurethane coating (PSPU) and inorganic hollow glass microsphere composite polyurethane coating (GSPU). Through research on raw materials, casting equipment, moulding and casting process, the prefabrication process of composite polyurethane insulation pipeline is determined, core parameters in the prefabrication are mastered and the composite polyurethane insulation pipeline is successfully prefabricated for the first time in China.Results of pipe materials sample testing and preliminary tests of product performance have reached technical requirements. Performance evaluation of the overall pipeline will be carried out in the later stage to applications of the composite polyurethane submarine insulation pipeline in domestic projects as soon as possible.