Taking one-year-old shoots of three wild species citrus of Guizhou Province as test materials and the shoots of cultivated variety Citrus reticulata as the control,we studied the changes of their membrane-lipid peroxidation,antioxidative enzyme activity,and organic osmoregulatory substance content under artificial cooling,aimed to analyze the differences of four kinds of citrus species in cold resistance.Semi-lethal temperature of wild citrus was determined by establishing Logistic regression model on leakage ratio of electrolyte.Finally,cold resistance of different citrus varieties was synthetically evaluated by using membership function method.(1)With the decrease of temperature,the ion leakage percentage of four kinds of citrus species increased in S-shape,and the SOD and POD activities,soluble protein,and soluble sugar contents decreased after an initial increase.The MDA content of C.ichangensis under decreasing temperature had an increasing trend.(2)The semi-lethal temperature(LT₅₀) of C.ichangensis,C.aurantium,C.limonnia,and C.reticulata calculated by the Logistic equation of ion leakage percentage was -14.86 ℃,-7.28 ℃,-8.45 ℃,and -5.88 ℃ respectively.The order of cold resistance evaluated by membership function method was basically identical establishing Logistic regression model.Among the four kinds of citrus species,C.ichangensis had the strongest cold resistance,followed by C.aurantium,C.limonnia,and C.reticulata,wild citrus has the stronger cold resistance than that of C.reticulata.