Abstract: Subcritical water technology attracted the attentions of scientists and researcher increasingly because of the characteristics, such as environmental-friendly, non-polluting, low cost. Water which maintains its liquid state from 100℃ to 374℃ by being compressed at moderate pressure, is so-called “subcritical water ”.Subcritical water owns special physical and chemical properties, such as low relative dielectric constant and high ion product. In this context, detailedly elaborated the concept of the subcritical water, and summarized the main applications of subcritical water, which was mainly used in the extraction of harmful ingredients from soil and in the extraction of useful component from by-products of agriculture, in the subcritical liquid chromatography, and in the chemical reaction of subcritical water.