Abstract: The cutting potted seedlings of 5 varieties (strains) of pitaya, namely Haibai No.1, Baijulong, Chilong, Julong and Hongxianmi were used as the experimental material, and the physiological and biochemical indexes including the relative conductivity of stalk under the NaCl stress, the content of malondialdehyde (MDA), soluble sugar and proline (Pro), and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were determined. With the salt tolerance coefficient of the indexes as the measure index, the salt tolerance was evaluated by using the method of principal component analysis. Three principal components were extracted by means of principal component analysis, which could explain 97.34% of the original variable information. Then, the salt tolerance evaluation system of different varieties (strains) of pitaya was established, and the salt tolerance of 5 varieties (strains) of pitaya was ranked:Chilong > Haibai No.1 > Julong > Baijulong > Hongxianmi.