Papain is high activity natural protease extracted from pawpaw pulp cut out from papaya cuticle via modern bioengineering technology. It is a natural biological product, having such two forms as liquid enzyme and solid enzyme, and such varieties as refined enzyme and rough enzyme. It is water and glycerin soluble. Its aqueous solution is colorless or presenting a light yellow color, sometime a creamy white color. The most suitable pH value is 5.7 (usually a pH value in between 3-9.5 is acceptable). It works even when it is in a neutral or slight acid condition. The isoelectrolytic point is 18.75. The most suitable temperature is 45-70oC (usually a temperature in between 10-85oC is acceptable). It is highly heat resisting, and will not totally lose its activity at a temperature as high as 90oC. It is restrained by oxidants and activated by reducing substances. It is a sort of endopeptidase containing (-SH), having extremely powerful biological activity and protein decomposing capability, and being able to decompose protein into micro-molecular peptide and amino acid in a quick and effective way. It has a composing function as well, being able to compose protolysate into proteinoid. Since papain has characteristics such as natural, environment protective, and safe to use, it is widely applied to the food, cosmetic, medicine, health food, feedstuff, leather, textile, daily chemical and aquatic product industries.