Under the increasingly severe global heat threat, continuous high temperature has far-reaching effects on plant growth and development and become a major constraint to crop production. The development of heat-resistant varieties has become research hotspot in many fields, and it is also necessary to establish effective identification methods. In this study, twenty Brassica rapa varieties were selected to to investigate the physiological and biochemical characteristics under heat stress, explore the relationship between physiological response and the heat resistance mechanism, select some typical heat-resistant and heat-sensitive varieties. The effects of photosynthetic electron transfer and antioxidant pathway on heat resistance of Brassica rapa were identified. These findings will providing an important reference for the physiological regulation and identification method of high-temperature stress in plants.