Increasing insulation thickness may reduce the energy consumption and environmental load in building operation phase, but may also increase those in insulation production phase. Therefore, the life cycle energy consumption and environmental load of insulation design for a typical residential building were analyzed in this paper. Cases in four typical cities -Harbin, Beijing, Shanghai and Guangzhou- in four different climate zones in China were compared. The results indicate that increasing insulation thickness based on the active design standards for buildings in Harbin, Beijing and Shanghai, is helpful to reduce building life cycle energy consumption and environmental load. But for buildings in Guangzhou, the insulation thickness should not be increased any more.