Abstract: 【Objective】 Field experiments were conducted to study the effects of drip application of acidifier on soil pH, available zinc, cotton root system, yield and quality in root zone, so as to screen out suitable acidifier types and dosage for local cotton production. 【Methods】 Three kinds of Acidifiers, ammonium sulfate (S), oxalic acid (C) and citric acid (N), were set as the test control (CK) without acid treatment. The dosage of ammonium sulfate and urea was determined by substituting 30%, 50% and 70% urea N for each top dressing. The same amount of H⁺ was provided by acidifier solution as the standard, and then the dosage of other Acidifiers was determined. 【Results】 In the vertical direction, soil pH decreased by 0.05-0.24 with the increase of acidifier application rate; in the horizontal direction, soil pH decreased by 2.3%-3.2% with the increase of ammonium sulfate application rate; no matter in the vertical direction or in the horizontal direction, the closer the distance from the emitter or the higher the proportion of ammonium sulfate replacing urea, the higher the content of soil available zinc; when 30%-70% of nitrogen fertilizer was replaced by ammonium sulfate, oxalic acid and lime decreased When citric acid was applied to cotton root zone with the same amount of H⁺, the dry matter of 0-30 cm root increased significantly compared with CK. The results showed that the dry weight of root system was S₃ > C₃ ≈ N₃ > CK; ammonium sulfate and oxalic acid had the largest accumulation of dry matter in cotton; compared with the control, the application of acidifier increased the single boll weight of cotton, significantly increased the number of bolls per plant, and the cotton yield increased with the increase of the proportion of ammonium sulfate replacing urea; compared with the control, acidifier promoted the increase of fiber length and specific strength, and reduced the uniformity and yield Micronaire value. 【Conclusion】 Among the three Acidifiers, ammonium sulfate is the best acidifier, and the proportion of replacing urea is 70%.