Abstract: The one-year-old dormant branches of nine walnut varieties（‘Liaoning 1’‘Xinxin 2’ ‘Xinzaofeng’‘Zhonglin 3’ ‘Baofeng’‘Jin Long 1’‘Xiaohe 1’‘Zha 343’ and ‘Luguang’） were used as test materials, the effects of different low temperature stress conditions（4,-20,-25,-30,-35 ℃ and-40 ℃） on the physiological and biochemical indexes such as relative electrical conductivity（REC）,soluble protein（SP）,superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） of nine walnut species were investigated by artificially simulated cooling stress treatments, and the physiological indexes of cold resistance of each walnut species were comprehensively evaluated by the affiliation function method, in order to provide reference for the selection of cold-resistant walnut species suitable for cultivation in Qinghai.The results showed that the relative conductivity of the nine walnut varieties gradually increased as the stress temperature decreased, and there were some differences in the trends of soluble protein, soluble sugar, CAT,SOD and POD.The nine walnut varieties were ranked in order of cold resistance by the subordinate function method, from highest to lowest ‘Liaoning 1’＞‘Zhonglin 3’＞‘Xiaohe 1’＞‘Xinzaofeng’＞‘Jinlong 1’＞‘Luguang’＞‘Baofeng’＞‘Zha 343’＞‘Xinxin 2’.