A method and a mixture for treating and preventing the inflammatory bowel disease (IBD) by applying a predetermined therapeutically effective amount of a mixture of hyaluronic acid to individuals is disclosed. The mixture includes at least two different average molecular weight hyaluronic acids (Mw) with different rheology to gain a hyaluronic acid with the proper adhesion property, functions of tissue scaffold and insulation and treatment time, in order to treat and to prevent IBD (inflammatory bowel disease) includes ulcerative colitis, Crohns disease or wound healing in stomach and intestine, thus to achieve the prompt treatment and to prolong the effect.