As a kind of commonly used traditional Chinese medicine, ginseng has a high reputation at home and abroad. The research of ginseng has been expanded to medicine, pharmacy, biology, food science and other fields, with great achievements in recent years. Ginseng contains ginsenosides, volatile oil, carbohydrates, amino acids, polypeptides, inorganic elements and othser chemical constituents. Each component has extensive physiological activity, and is the base of ginseng's effect. After processing, the complicated changes are taken place in the constituents of ginseng, and some new substances produced. This paper aims to review the studies on chemical constituents and their mechanisms during ginseng processing, and the ideas, methods and the direction of the development of traditional Chinese medicine processing in the future.