The density of high-density chitosan (≥0.8g/ml) is twice or three times as high as comm on chitosan. The oil-absorbing ability is over three times of common at the same volume. One capsule is enough to dissolve and absorb fat, cholesterin and chloride ion effected by hydrochloric acid in gastric juice, which will be directly exreted to the outside of the body to reach the aim of losing weight, reducing blood fat and decreasing blood pressure.