Abstract: 【Objective】 This project aims to study the changes of photosynthetic characteristics, resistance indexes and plant hormones of upland cotton GhCIPK6 transgenic offspring under high temperature stress in order to lay a foundation for upland cotton to respond to high temperature stress. 【Methods】 In this experiment, the overexpression of ghc1pk6 transgenic offspring, RNAi and control wild type were constructed as materials. The physiological and biochemical indexes were measured at 4 h, 12 h, 24 h and 48 h by greenhouse culture. 【Results】 Through the comparison of seedling leaves, it was found that the overexpressed leaves had turned yellow and a large number of spots appeared under high temperature, followed by wild-type leaves, and RNAi leaves only slightly turned yellow;In the photosynthetic characteristics, under high temperature stress, with the extension of time, the net photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO₂ concentration decreased first and then increased. The overexpression materials increased slowly in photosynthetic indexes, RNAi and wild-type increased rapidly, and the change trend of chlorophyll relative content was slow; Among the resistance indexes, under high temperature stress, overexpression increased gradually with the extension of time, SOD content increased first and then decreased and then increased, pod content showed a high level, MAD content in RNAi increased first and then decreased, SOD content increased first and then decreased, pod content increased slowly, soluble protein content and Pro content showed a relatively high level in the whole period; In plant hormones, with the extension of time, the content of IAA in overexpression materials showed an upward trend, the content of ABA was low, the content of JA first increased slowly and then decreased, SA first increased and then decreased, the content of IAA in RNAi materials gradually increased, the content of ABA first increased and then decreased, the content of JA first increased and then decreased, the content of SA first decreased and then increased and then decreased, the content of IAA in wild type first increased and then decreased, and the content of ABA first increased and then decreased and then increased, JA content first increased and then decreased, SA content first decreased and then increased and then decreased. The resistance to high temperature of the three materials from strong to weak was RNAi, wild-type and overexpression. 【Conclusion】 The comprehensive results show that under high temperature, the harm of stress can be reduced by increasing transpiration rate, the growth of plants can be actively regulated by increasing auxin content, and the osmotic regulation ability of cells can be improved to reduce the damage of cells.