The aim was to study the cold-resistance mechanism of evergreen broadleaf trees. Taking three evergreen broadleaf trees of Euonymus as the research object, lethal temperature 50 (LT50) was calculated with logistic formula through determining electrolyte leakage rate. The influence of cold stress on POD activity, soluble sugar contents and proline contents was investigated. The resuLTs showed that electrolyte leakage rate increased, POD activity and osmotic regulation substances such as soluble sugar contents first up then down along with cold stress increased. There was obvious difference in cold resistance of congeneric and different species. The cold resistance of three evergreen broadleaf trees from strong to weak was: E. japonicus. ‘CuZhi’, E. japonicus.‘Aoxue’, E. japonicus, and its lethal temperature 50 respectively was -28.27℃, -26.42℃, -25.70℃.