This experiment takes Bupleurum chinense DC.,Bupleurum chinense DC.(lushi) from Lushi of Henan Province and Bupleurum falcatum L.roots as the materials.In early spring,with the survival rate of plants as winter hardiness indexes,the physiological and biochemical indexes of different varieties of Bupleurum root were detected during winter period.Path analysis and phase analysis were used to evaluate Bupleurum cold resistance and cold resistance physiological indicators.The purpose is to explore the relationship between dynamic changes and cold resistance physiological indexes of Bupleurum in natural low temperature conditions and to filter out the most suitable physiological indicators that identify Bupleurum winter hardiness.The results as follows:(1)The overwinter survival rate in turn was 80%(B.chinense DC.),50%[B.chinense DC.(lushi)],10%(B.falcatum L.),and there were differences between different cultivars.(2)The change of soluble sugar content,proline content,soluble protein content and root activity were consistent with that of the overwinter survival rate,but the relative electrolytes and MDA content of the 3 cultivars were in an opposite order.Among them,the free proline content of B.chinense DC.was 2.44 fold of B.chinense DC(lushi).and 4.49 fold of B.falcatum L..The soluble protein content of B.chinense DC.was much higher than that of others.(3)During natural overwintering,the root activities of all cultivars showed a decreasing trend.The decrease margin of B.falcatum L.was the largest(80%),the decrease margin of B.chinense DC.was the smallest(52.04%).(4)The winter hardiness of three Bupleurum species of comprehensive order was:B.chinense DC.>B.chinense DC.lushi>B.falcatum L.,the comprehensive appraisal was significantly positively correlated with the contents of protein and proline,but it had significant negative correlation with the relative electrolytes.The decision coefficient of physiological indexes in size order was proline content>soluble protein content>conductivity.The results showed that:the free proline content of roots was the main factor which influenced cold resistance during natural overwintering,which could be used as evaluation index of cold resistance of Bupleurum.