Abstract: 【Objective】 To investigate the effects of potash fertilizer distribution and dosage in cotton production and clarify the most suitable potassium application level for cotton growth under drip irrigation under membrane in Xinjiang. 【Methods】 Four potash dosages were set, i.e., 60, 90, 120 and 150 kg/hm² of pure potassium (K₂O), which were expressed as K₁, K₂, K₃ and K₄, respectively; and two kinds of potash fertilizers, i.e., potassium sulphate and potassium sulphate+potassium humate (1:1 ratio), which were expressed as A and B, with eight treatments in total, and no potash fertilizers were applied to CK as the control. 【Results】 The experiment showed that plant height of cotton in all treatments was greater in AK₄ treatment, but not significantly different from BK₄. Stem thickness reached the maximum in BK₄ treatment, but there was no significant difference with AK₃, AK₄ and BK₃;SPAD value showed a trend of increasing and then decreasing in each treatment, and reached the maximum in AK₄ treatment in the boll stage, but there was no significant difference with AK₃, BK₃ and BK₄; Dry matter accumulation increased slowly and then rapidly with the progress of fertility, and reached the maximum at the full-bell stage, and the dry matter accumulation of BK₄ treatment was the highest among all treatments, but there was no significant difference with AK₃, AK₄ and BK₃; Intercellular CO₂ concentration and net photosynthetic rate at the boll stage increased with the increase of fertilizer application, and transpiration rate and stomatal conductance decreased and then increased with the increase of fertilizer application. The seed cotton yield of both potash treatments increased with the increase of fertilizer application, and the BK₄ treatment had the highest yield, but there was no significant difference with AK₃, AK₄ and BK₃. 【Conclusion】 Considering the factors together, potassium sulfate compounded with potassium humate treatment is superior to potassium sulfate treatment alone, and BK₃ treatment is the best treatment.