In recent years, β-glucan has been widely researched in various related fields due to its significant physiological activity and health characteristics. β-glucan exists in highland barley, barley, oats, and microorganisms such as yeast, bacteria fungi and other natural plants, and is a kind of renewable polysaccharide with high nutritional values. Different physical properties due to its extensive sources also affect the development and application of β-glucan in various bioactive functional fields. We have reviewed different sources of β-glucan and its structure-activity relationship, and summarized its research status in digestive system, nervous system, immune system and other aspects, indicating that β-glucan has special physiological activities such as regulating glucose and lipid metabolism disorders, improving immunity and brain function, regulating intestinal microenvironment. It can be used as a dietary supplement and functional factor to intervene and regulate body health, and also has broad application value and prospects in the field of health product research and development. This review will provide theoretical reference and scientific basis for the further development and utilization of β-glucan.