Soil salinization is an important factor contributing to the deterioration of soil environment and low crop yield in arable land. In this study, the effects of five fulvic acid applications (0 (CK), 150 (T1), 300 (T2), 450 (T3), and 600 (T4) kg·ha−1) on soil physicochemical properties, humus content of each component, and cotton (Xinluzao No. 82) growth were investigated. It was confirmed that fulvic acid improved soil water-stable macroaggregates, moisture distribution, and desalinization. 0–20 cm soil relative desalinization rate was significantly increased by 2–11.75%. The pH value decreased by 0.09–0.21. The soil organic matter content was significantly increased compared to CK (p p p p −1 fulvic acid. The results of this study can provide a theoretical basis for the improvement of saline soils in arid zones to enhance crop growth and yield.