Abstract: 【 Objective 】 The aims of this study is to reveal the effects of drought stress on photosynthetic characteristics of cotton and provide theoretical support for drought resistant breeding of cotton by studying the differences of photosynthetic characteristics among different cotton cultivars under drought stress.【 Method 】16N2, 16N3, 16N4, 16N5 and Yuanmian 6, a total of 5 varieties were taken test materials to measure the photosynthetic traits of the net photosynthetic rate, transpiration rate, stomatal conductance and photosynthesis and water utilization rate and study the difference and correlation between them both under the drought stress and normal irrigation conditions.【 Result 】The result showed that the photosynthetic characteristics of 5 cultivars decreased compared with the irrigation conditions, the drought resistance coefficient of cultivars was different in different varieties, of which photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency of 16N2 were higher than those of others.【 Conclusion 】Drought stress treatment could decrease photosynthetic physiological indexes such as transpiration rate, stomatal conductance and photosynthetic rate except photosynthetic water use efficiency. Through comparative analysis of the varieties, it has been found that the variety with the highest drought resistance coefficient and strong drought resistance was 16N2, which could be used as the intermediate material for drought resistance breeding. This research has also laid a foundation for drought resistant pyramiding breeding.