In order to clarify the protective effect of epidermal wax in the physiological response to nonheading Chinese cabbage under high temperature stress, we used waxy (Q28) and waxless (Q1202) varieties of nonheading Chinese cabbage as experimental materials under high temperature stress in this study. The experiment set the high temperature stress group (day/night temperature of 37 ℃/30 ℃) and control group (day/night temperature of 25 ℃/18 ℃) to observe the morphology of leaf epidermal cells of different materials. Measure and compare the differences in physiological and photosynthetic index changes in different periods of high temperature stress. The results showed that: (1) the biomass of the two nonheading Chinese cabbage seedlings was inhibited from varying degrees under high temperature stress, and the decline in the waxy material was smaller; the leaf epidermal cell morphology also had a big difference. The shrinkage of epidermal cells of the material leaves was significantly lower than that of the waxfree material. (2) The contents of proline, soluble sugar and soluble protein in the waxed material leaf was significantly higher than that of the waxfree material at 9 days of high temperature stress. (3) The antioxidant enzyme activities of the two materials showed a dynamic change that first increased and then decreased, and the activities of the waxy material were greater; the malondialdehyde content and relative conductivity of the two materials showed an upward trend, and the waxy material increasedless. (4) The chlorophyll content of the leaves of the two materials showed a downward trend, but the waxy material was still higher; compared with the waxfree material, the waxy material leaves had a lower transpiration rate and a higher net photosynthetic rate. Studies have revealed that under high temperature stress, leaf wax can improve leaf osmotic adjustment ability, protect the normal morphology of leaf epidermal cells, and enhance plant antioxidant capacity.