Organic fertilizers with humic acid as the main component are widely used materials for improving saline-alkali soils. However, the improvement effects vary significantly with different application rates and methods under different degrees of salinization. In this study we collected 43 relevant research findings from the past decade (2012—2023), explored the effects of different humic acid application rates (low, medium, high) and application methods (alone, mixed with other amendments) on saline-alkali soil with different salinized degrees (low, medium, high). The results showed that, compared with not applying humic acid, applying humic acid significantly reduced pH value by 3.22%-3.80% of saline-alkali soil, increaseed the content of Ca²⁺ by 11.43%-50.46%. Soil Mg²⁺ content rose by 8.15%-28.52% overall at different humic acid application rates. The application of medium and high amounts of humic acid reduceed soil Na⁺ and Cl^- contents by 11.5%-11.59% and 14.16%-18.73%, respectively. In terms of humic acid application methods, the effects of humic acid application alone and combined application were not significantly different in low and high saline-alkali soils, while the effect of humic acid application combined with other amendments was better than that of single application in middle saline-alkali soil, and the synergistic effect between different amendments further promote the improvement effect. The effect of humic acid dosage on saline-alkali soil improvement was affected by saline-alkali degree. Low amount of humic acid (≤600 kg/hm²) could be added to improve yield in low saline-alkali soil, high amount of humic acid (≥1 800 kg/hm²) could be applied to reduce salt ions and increase yield in middle saline-alkali soil. However, for the high saline-alkali soil, the improvement should be divided into two stages, in the early stage, the application of medium amount of humic acid (600%-1 800 kg/hm²) has the best salt ion reduction effect, and the application of high amount of humic acid after salinization control in the later stage can further improve the productivity. This study provides a theoretical basis for determining the appropriate dosage range and application mode of humic acid and provides important theoretical support for the improvement and comprehensive utilization of saline-alkali soil.