Extracellular polymeric substances (EPS) are high-molecular-weight natural polymers secreted by microorganisms into their surrounding environment. EPS establish the structural and functional integrity of biofilms, and are the key component that determines the physicochemical properties of biofilms. As the basis of bacterial life activities, EPS can provide an ideal environment for chemical reactions, nutrient capture, and resistance to environmental stress. EPS secreted by bacteria can benefit soil functions through its properties (such as adhesiveness, hydroscopicity, and complexation), e.g. increasing aggregate stability, enhancing water retention, and fixing heavy metals. Therefore, in-depth research on soil EPS is key to better management of biologically mediated nutrient turnover and soil health. To this end, this review first introduces the concept, components, and controlled factors of EPS, and especially emphasizes the interdisciplinary consistency of the term EPS. The paper then summarizes the soil ecological functions of bacterial EPS:1) Act as cells' protection layer, such as preventing cell desiccation, maintaining the stabilization of extracellular metabolism, and affecting the adhesion process of cells on the solid surface; 2) Regulate biological response, such as assisting the symbiosis between bacteria and plants, resisting the sterilization of antimicrobial compounds, and influencing genetic material transfer; 3) Alleviate abiotic stress, such as enhancing the water-holding capacity of soils, improving salt tolerance of organisms, and adapting microbes to extreme environments; and 4) Improve the overall functions of soil, such as driving soil particle aggregation, promoting soil aggregates stabilization, achieving the capture of nutrients and extracellular storage, holding heavy metals and reducing them by acting as electron transfer media and electron donors, and adsorbing organic pollutants and accelerating their biodegradation. Finally, we suggest future research opportunities of bacterial EPS in soil:a) Promote the specific extraction and accurate analysis of soil EPS; b) Clarify the relative contribution of EPS-protein and Glomalin-related soil proteins to soil aggregates stability; c) Evaluate the relative importance and correlation between soil EPS and other soil health indicators; d) Consider the benefits of bacterial EPS for the research and development of novel biofertilizers. This review calls for more scholars to pay attention to and study bacterial EPS and its functions in soil ecosystems, and to explore its potential application in the development of environmental-friendly agriculture.