Abstract: 【Objective】 To study the effects of different concentrations of CaCl₂ on the morphological changes and physiological characteristics of muskmelon seedlings under high temperature and strong light in autumn field in Turpan area, so as to provide reference for determining the optimal application concentration of CaCl₂, and improving the stress resistance of muskmelon seedlings and the whole seedling and strong seedling rate of melon. 【Methods】 Four treatments were set up to study the physiological characteristics of muskmelon Xizhoumi 17, which were sprayed with 20, 10 and 5 mmol/L, respectively. The effects of different concentrations of CaCl₂ on physiological characteristics of muskmelon seedlings were analyzed. 【Results】 Under high temperature condition, with the growth and exercise of seedlings, the soluble protein content of muskmelon leaves showed a three-stage "S" curve of "slow decline-rapid rise-slow rise", the relative content of chlorophyll always increased, and the antioxidant enzyme activities (SOD, POD, CAT) and MDA content first increased and then decreased. Soluble protein content, antioxidant enzyme activities (SOD, POD, CATt) and MDA content increased significantly, then decreased rapidly from 3-leaf stage to 5-leaf stage, and slowly decreased or fluctuated in a certain range from 5-leaf stage to 9-leaf stage. 【Conclusion】 Spraying 5 mmol/L CaCl₂ can increase the relative content of chlorophyll and soluble protein by 17.70% and 23.61% respectively, and the activities of SOD, pod and cat are increased by 115.79%, 57.42% and 53.52% respectively, and the content of MDA is decreased by 22.13% compared with the control.