The invention relates to the field of medicine, and specifically discloses an enteric-coated gastro-retentive oral dosage form in tablet form, and applications and a pharmaceutical composition thereof. The oral dosage form includes: a. a bile acid chelating agent selected from colesevelam and colesevelam hydrochloride; b. a polymeric matrix comprising a poly(alkylene), the bile acid chelating agent being dispersed in the polymeric matrix; c. one or more fillers or compression agents selected from microcrystalline cellulose, lactose, starch, maltodextrin, and dicalcium phosphate, wherein the oral dosage form slowly releases the bile acid chelating agent into a stomach. The dosage form is capable of providing the bile acid chelating agent to the stomach in long-lasting and stable level, theconcentration of the bile acid chelating agent permitting the bile acid chelating agent to optimally combine with bile acids refluxing from a small intestine to the stomach, thereby avoiding damages of a gastric mucosa caused by bile acids, and preventing the bile acids in the stomach from refluxing to an esophagus and other parts of an upper digestive tract and a throat, to prevent further damage.