Abstract: Taking six peony varieties（‘Huhong’‘Yaohuang’‘Luoyanghong’‘Yinhongqiaodui’‘Yuhoufengguang’‘Jindao’） as test materials.The physiological response mechanism of osmoregulation substance,MDA,■content and antioxidant enzyme activity in leaves under drought was studied,and the comprehensive resistance evaluation was carried out by membership function method.In order to explore the regulation mechanism of osmotic adjustment substances and antioxidant system in tree peony leaves under drought stress,and evaluate the resistance relationship among varieties by using these resistance indexes.The results showed that the content of proline,soluble protein,MDA,■and the activity of SOD in the leaves of six peonies increased with the increase of drought degree.Soluble sugar content first decreased and then increased.The activity of POD and CAT increased in the early stage and decreased in the later stage.In severe drought,the content of proline and soluble protein in ‘Yaohuang’‘Huhong’ increased the most,‘Luoyanghong’‘Yinhongqiaodui’‘Yuhoufengguang’‘Jindao’ had a smaller increase.The contents of MDA and ■ in the leaves of ‘Huhong’ and ‘Yaohuang’ were lower,and the damage was lighter than the other four varieties.The APX activity of ‘Huhong’‘Jindao’‘Yaohuang’ increased gradually with the increase of stress degree,while that of ‘Yuhoufengguang’‘Luoyang hong’‘Yinhongqiaodui’ increased first and then decreased.After rehydration,the physiological function of peony was restored,the content of MDA and ■ were significantly reduced,and the damage of drought stress was effectively alleviated.According to the comprehensive evaluation of subordinate function method,the order of drought tolerance ability from strong to weak was ‘Huhong’‘Yaohuang’‘Jindao’‘Yuhoufengguang’‘Yinhongqiaodui’‘Luoyanghong’.It could be seen that under drought stress,peony could effectively enhance its osmotic regulation function,reduce the damage of drought stress through its own antioxidant mechanism.These resistance indexes could be used to evaluate the resistance relationship among varieties.