Abstract: Temperature of diagrams of supercooling water phase change in the polar 1-69 and 1-45 bodies have been tested menswrated by DAT, NMR and ESR. Based on the analyzing temperature of the diagrams, the tested temperature by three different methods are unani mous. Two species second freeze temperature was gave respectively. Poplar 1-69 second freeze temperature is about-14℃, and poplar 1-45 is about--20℃. The cold resistance of poplar 1-45 is superior to that of poplar 1-69.