Abstract: Five tree species in Magnoliaceae family and one tree species in Aquifoliacea family in different ages were selected to study the cold resistance by measuring electric conductivity under simulated low temperature.Meanwhile the semi-lethal temperature of these tree species were evaluated from Logistic equation to indicate their cold resistance.The results showed that the semi-lethal temperature of each tree species sampled by the end of Dec.2003 was generally lower than that of sampled at the beginning of Sept.2003.The difference of the semi-lethal temperature of these tree species sampled at the beginning of Sept.2003 was less(-5.03℃~-6.08℃)than the difference of the semi-lethal temperature of the specimen sampled by the end of Dec.2003(-9.86℃~-13.48℃).The semi-lethal temperature of each tree species was generally below-11℃ after over-wintering hardening except 3-year-old Michelia chapaensis and Michelia foveolata, whose semi-lethal temperatures were little higher than-10℃.It was showed that the cold resistance of these tree species increased along with the increment of the plant age.The cold resistance of the 6 tested tree species could be ordered as:Michelia maudiae >Michelia platypetala >Manglietia yuyuanensis >Ilex latifolia >Michelia foveolata >Michelia chapaensis.The feasibility to introduce these tree species into Nanjing area was also discussed.