At present, there is a widespread shortage of potassium in the soil, especially in the cotton-planting areas because of the thin ground and poor fertility, coupled with neglecting the input of potash fertilizer in the habit of fertilization, resulting in different degrees of potassium deficiency symptoms in cotton, which seriously affect the quality of cotton and reduce the yield. From the production practice of planting insect-resistant cotton in recent years, it is known that insect-resistant cotton is more sensitive to potash fertilizer, and potassium fertilizer is added to prevent physiological red stem blight and premature aging of cotton, thereby improving cotton quality and increasing yield. According to experiments, the ratio of NPK is 1 to 0.5 to 1 to 1 to 0.5 to 0, and 7.1 percent of lint is increased. Therefore, we should vigorously promote the application of potash fertilizer to insect-resistant cotton. At the same time, we must pay attention to the input of phosphate fertilizer and trace fertilizer, and adjust the ratio of nitrogen, phosphorus and potassium to 1 to 0.5 to 05 to 10.