Antibodies are Y-shaped proteins secreted to identify and neutralize pathogenic microorganisms, such as bacteria and viruses, which maintain our health. Oral antibodies that enter the intestinal tract provide intestinal passive immunity to protect the intestinal tract from infection by pathogenic microorganisms. In recent years, a growing number of studies have shown that the gastric environment does not affect some specific antibodies, which provide immediate protection in an animal’s gut. The development process, action mechanism, preparation route, and stability characteristics of oral antibodies are introduced and the protective effect of natural antibodies and genetically engineered antibodies on intestinal infections in animals by oral intake are summarized in accordance with the practical application.