Abstract: Seventeen cauliflower genotypes were subjected to heat stress to study the effects on 3 agronomical and 6 physi-biochemical traits. Using the principal component analysis, subordinate function and system clustering analysis on these 9 traits, heat tolerance of the genotypes was evaluated. The principal component analysis indicated that the 9 indices could be characterized into 5 factors with an accumulative contribution rate of up to 0. 877. Based on the D value of subordinate function analysis, the 17 genotypes were divided into 3 clusters by system clustering analysis. The most heat tolerant genotype was H1-3Y-H, the medium tolerant genotypes were ZF1-H, 14, A-118-3, 18-2-2-4s, 143-4-1-1-5-4s, A-422-2, A-25H1-2, H1♂-2Y, 142-2-5 and A3A19-2, and the lest tolerant genotypes were B-1H-1-3-2, C-519-1, C-1196-6, A6A19-2, C-519-1A36-5 and B-210-2. The selection and evaluation methods developed in this study provided a useful tool for further study on heat tolerance and breeding of cauliflowers.