The design life of cold and hot water supply pipe in general civil building is 50 years, and 100 years are required in some municipal engineering. The service life of plastic pipe depends on the plastic material itself, and is closely related to the working temperature of the pipeline, the working pressure and the wall thickness of the pipe. It should be said that in a reasonable temperature range, under certain working pressure, choose the appropriate thickness of PEX pipe and PPR pipe, its service life can be more than 50 years. In this regard, we must pay attention to the three premises. According to the plastic material long term performance test standard ISO/TR9080-1992, the conclusion derived from the theoretical point of view is that the service life of PEX and PPR pipes can be guaranteed for 50 years in the temperature range of 70 degrees centigrade. From the German standard DIN16892/3, it can be seen that the continuous working temperature limit of PEX pipe is 80 DEG C under the condition of ensuring the service life of 50 years, and the continuous working temperature limit of PPR pipe is 70 degrees centigrade.