Abstract: 【Objective】 To explore the changes of related indicators and the number of microorganisms during the maturation process of cotton straw with different additive formulas. 【Method】 In this experiment, cotton stalks were used as raw materials, and different additive formulas were set up to perform cotton stalk compost composting and fermentation. The fermentation-related indicators (temperature, pH, electrical conductivity, available nitrogen, phosphorus, and potassium concentrations) and major microbial changes were measured and analyzed. 【Result】 The results showed that the trends of temperature, pH, electrical conductivity, and available nitrogen, phosphorus, and potassium of the three treatments were basically the same, but the relative contents were different, and the number of microorganisms under different treatments were also different. 【Conclusion】 Treatment 3 (basic formula + 2% potassium dihydrogen phosphate 2%) was the best. The pH value was 8.59-8.89 and EC value was about 4 ms/cm, which was more suitable for composting fermentation.