Abstract: 【Objective】 This project aims to study the effects of application of matrine, microelement and amino acid-based compound fertilizer to control and treat the cotton leaf mite, and determine the best time of using them. 【Method】 The dynamics of the cotton leaf mite was investigated by field cell test in different application periods.【Results】 The results showed that the control rate of the compound agent containing amino acids to cotton leaf mite was 60% and 90.82% respectively in 2017 and 2018. The anti-mite rate of matrine single agent was 47.13% and 72.4%, which was significantly higher than that of matrine single agent (P<0.01).The yield of compound fertilizer treatment with amino acid was 142.11 and 245.5 kg/240m² respectively, which was 33%, 12.49%, 15.27%, 10.40% and 43.10% respectively higher than those of other treatments. There was no significant difference between matrine treatment and control treatment. In addition, there were significant differences in plant height, stem thickness, single boll weight, dry matter and falling boll. 【Conclusion】 The application of biological fertilizer compound agent is suitable for wide application in cotton field, which plays an important role in controlling cotton leaf mites and increasing yield.