Abstract: To understand the drought resistance of five main walnut varieties in Sichuan Province. The main physiological and biochemical indexes of leaves were measured by natural drought treatment, and then the drought resistance was comprehensively evaluated by principal component analysis and membership function method. The analysis result of physiological and biochemical indexes of five walnut varieties showed that the relative water content (RWC) and chlorophyll content (Chl) decreased with the extension of drought time. The activities of catalase (CAT), peroxidase (POD) and malondialdehyde (MDA) showed a trend of increasing first and then decreasing, and the overall performance was increased or decreased. However, the activity of superoxide dismutase (SOD) increased firstly and then decreased or gradually increased. The results of correlation, principal component and membership function analysis showed that Chl, MDA and SOD activity could comprehensively evaluate the drought resistance of five walnut varieties. By measuring the physiological and biochemical indexes of five varieties, the order of drought tolerance of the five walnut varieties was as follows: 'Xinxin2' > 'Wen185' > 'Yangbi' > ' Yanyuanzao' > 'Santaipao'.