This article investigates the physicochemical characteristics and biological functions of insoluble dietary fiber (IDF) extracted from legumes. Legumes are rich sources of IDF, which are primarily found in the structural cell walls and outer integument, characterized by their high fiber content and diverse bioactive compounds. IDF exhibits strong hydrophilic properties, enabling water absorption and volumetric expansion, which contributes to increased food bulk and viscosity, enhancing satiety and accelerating gastrointestinal transit. The benefits of IDF extend to its antioxidant, anti-inflammatory, and anti-cancer properties, as well as its ability to modulate the intestinal microbiota, promoting the growth of beneficial bacteria and suppressing harmful pathogens. IDF is also valued in food processing as a thickening agent, stabilizer, and emulsifier, contributing to the texture and stability of various food products. The article reviews the structural composition, physicochemical properties, and applications of IDF from legumes. IDF is a complex polysaccharide system, comprising cellulose, hemicellulose, and lignin. These components form the robust structure of IDF, with variations in monosaccharide composition across different legumes. The physicochemical properties of IDF, such as water holding capacity (WHC), oil holding capacity (OHC), and swellability, are influenced by the structure and nature of water-binding sites. Studies have shown that IDF from legumes exhibits excellent WHC and OHC, making it suitable for use in food products. The biological functions of IDF include improving gut health, preventing obesity, intervening in glycolipid metabolism, preventing cardiovascular disease, and preventing cancer and malignant diseases. IDF facilitates intestinal peristalsis, enhances intestinal flora structure, and adsorbs detrimental substances. It also demonstrates oil adsorption capabilities, swelling properties, and the ability to influence lipid metabolism, contributing to weight management and reduced blood lipid levels. Additionally, IDF has been found to prevent cardiovascular disease by regulating lipid metabolism and lowering blood sugar levels. Its anti-cancer properties are attributed to its robust adsorption capacity towards harmful substances and immunomodulatory properties. The article also discusses the application of IDF in food processing, highlighting its use as a thickening agent, gelling agent, and stabilizer in various food products. IDF's mixed gelatinization properties and hydrophilic nature make it valuable in maintaining moisture retention and structural integrity in processed foods. Overall, the article emphasizes the multifaceted role and profound impact of IDF on human health and its potential for high-value utilization in the food industry.This article investigates the physicochemical characteristics and biological functions of insoluble dietary fiber (IDF) extracted from legumes. Legumes are rich sources of IDF, which are primarily found in the structural cell walls and outer integument, characterized by their high fiber content and diverse bioactive compounds. IDF exhibits strong hydrophilic properties, enabling water absorption and volumetric expansion, which contributes to increased food bulk and viscosity, enhancing satiety and accelerating gastrointestinal transit. The benefits of IDF extend to its antioxidant, anti-inflammatory, and anti-cancer properties, as well as its ability to modulate the intestinal microbiota, promoting the growth of beneficial bacteria and suppressing harmful pathogens. IDF is also valued in food processing as a thickening agent, stabilizer, and emulsifier, contributing to the texture and stability of various food products. The article reviews the structural composition, physicochemical properties, and applications of IDF from legumes. IDF is a complex polysaccharide system, comprising cellulose, hemicellulose, and lignin. These components form the robust structure of IDF, with variations in monosaccharide composition across different legumes. The physicochemical properties of IDF, such as water holding capacity (WHC), oil holding capacity (OHC), and swellability, are influenced by the structure and nature of water-binding sites. Studies have shown that IDF from legumes exhibits excellent WHC and OHC, making it suitable for use in food products. The biological functions of IDF include improving gut health, preventing obesity, intervening in glycolipid metabolism, preventing cardiovascular disease, and preventing cancer and malignant diseases. IDF facilitates intestinal peristalsis, enhances intestinal flora structure, and adsorbs detrimental substances. It also demonstrates oil adsorption capabilities, swelling properties, and the ability to influence lipid metabolism, contributing to weight management and reduced blood lipid levels. Additionally, IDF has been found to prevent cardiovascular disease by regulating lipid metabolism and lowering blood sugar levels. Its anti-cancer properties are attributed to its robust adsorption capacity towards harmful substances and immunomodulatory properties. The article also discusses the application of IDF in food processing, highlighting its use as a thickening agent, gelling agent, and stabilizer in various food products. IDF's mixed gelatinization properties and hydrophilic nature make it valuable in maintaining moisture retention and structural integrity in processed foods. Overall, the article emphasizes the multifaceted role and profound impact of IDF on human health and its potential for high-value utilization in the food industry.