Low-molecular-weight organic acids are widely present in soil, and have important effects on soil structure, nutrient cycling, pollutant migration and transformation, and even soil ecological functions. Free radicals in soil participate in organic matter decomposition and element balance regulation through redox reactions, affecting soil fertility and ecological balance. In recent years, the impact of low-molecular-weight organic acids on the generation mechanisms of free radicals has attracted significant attention. This article introduced the sources, types, and roles of low-molecular-weight organic acids and reactive oxygen species (ROS) in soil, discussed the impact of low-molecular-weight organic acids on ROS, further explored the important significance of this process in pollutant transformation and element cycling, and looked forward to the future research directions and development trends of low-molecular-weight organic acids regulating soil free radical processes.