Abstract: Protein content, peroxidase(POD), catalase(CAT) activity and transpiration rate were measured to determine the heat tolerance of three lily genotype leaves at seedling stage. The results showed that protein content decreased continuously. POD and CAT activities showed a transient rise. Those physiology indexes were worse of heat sensitive genotype, which indicated the three indexes were positively correlative with heat tolerance. Transpiration rate showed invisible correlation with heat tolerance.