Rigid polyurethane insulation layer is widely used in construction, household appliances, automobiles and aerospace, and the preparation process of thermal insulation layer has an important impact on environment. Therefore, it is of great significance to evaluate the environmental impact of the preparation process. The environmental impacts of the preparation process was conducted using ReCiPe method. It is confirmed that the thermal insulation layer preparation process has the greatest environmental impact on marine eco-toxicity, followed by human toxicity, freshwater eco-toxicity, freshwater eutrophication and fossil depletion. Paint, electricity, polyurethane and polyurea contribute greatly to the environmental impact, and the environmental impact results are most sensitive to paint and electricity. The painting process, the polyurethane and the polyurea spray process contribute more than 70% of the total result. The key factors that reduce the environmental impact include considering the recycle of polyurethane in design phase, avoiding waste of polyurethane and polyuria, using powder paint, improving efficiency of electricity and increasing the proportion of clean energy.