Abstract: Plant derived bioactive substances such as polyphenols and polysaccharides play an important role in functional and health food because of their antioxidant and anti-tumor properties. Polysaccharides and polyphenols are closely linked with proteins and lipids through non-covalent bonds such as hydrogen bond and water release bond. How to extract bioactive components from plant tissue by green and efficient method has become a hot research topic in food industry. Subcritical water is not only close to the ability of organic solvents to dissolve bioactive substances, but also can weaken the close combination between polysaccharides, polyphenols and other substances. It has the characteristics of non-toxic, pollution-free, solvent-free residue, and can be widely used in the extraction of bioactive substances. In this paper, the characteristics and influencing factors of subcritical water extraction technology are introduced, especially the effect and mechanism of subcritical water extraction of bioactive substances from plants, and the advantages of its combination with physical technology (such as microwave, ultrasound, intense pulsed light). This provides technical support for the efficient preparation of bioactive substances, and also provides theoretical basis and reference for the application of subcritical water technology in food.