Abstract: Leaf cold resistance abilities of mangrove species along the eastsouthern coast of China had been measured by conductivity method. The results show: (1)The cold resistance abilities (LT50) of 16 mangrove species at Dongzhai Estuary,Qiongshan. Hainan province were from -2.3 ℃ to -6.8℃. The species from Rhizophoraceae had higher cold resistance abilities than that from Sonneratiaceae and Meliaceae, so most of them could be classified into low cold sensitivity type (L type) ,and the late ones into high cold sensitivity type (H type). (2)As the latitude increased, the cold resistance abilities of Kandelia candel and Aegiceras corniculatum also increased, and reflected the trend of population differentiation(except one location). (3) At the same location, Kandelia candel and Aegiceras corniculatum had the lowest cold resistance abilities in summer, and higher cold resistance abilities in autumn and winter than those in spring. (4) Among the same mangrove community, Kandelia candel plants growing in the middle tidal zone had higher cold resistance ability than those in the high tidal zone, but no this difference was found in Aegiceras corniculatum. (5) Kandelia candel and Aegiceras corniculatum leaves had different cold resistance abilities according to their locations on the community crown. The cold resistance ability of leaves decreased from upper surface to lower layer, and from surface to inner part. The population differentiation ,season changes ,and leaf location variation of mangrove cold resistance abilities were due to the ecological adaptation to various habitats which were beneficial for the survival and regeneration of mangroves.