Medicinal gelatin is a water-soluble polymer substance obtained by moderately hydrolyzing and thermally denaturing collagen proteins present in animals. It is a protein with a relative molecular mass between 2X104 ～ 4.5X105, and it is the most important protein component in animal skin, bone, and tendon. 98%.

Medicinal gelatin collagen is the primary layout protein that exists in all animal skins and bones. Collagen molecules are composed of three polypeptide chains, which surround each other to form a three-stranded spiral layout. In the α chain of the collagen molecule, the hydrogen bond existing between the carboxyl group and the amino group can stabilize the triple-stranded helix.

With the increase of animal age, the covalent bonds existing between collagen molecules make collagen molecules up to 3000nm in length and 150 nm in diameter. Each alpha chain has about 1050, a total of 20 kinds of amino acids combined with each other.