Expert systems have been widely used to solve problems in various fields such as medicine, mathematics, engineering, chemistry, pharmacy, computer science, business, law, education, and defense. If the expert system is related to the doctor's ability to diagnose the patient's health, a computer system can be created that can identify and analyze the symptoms that occur in patients and provide suggestions for overcoming them. Worms seem trivial, but if we look closely, it has a serious impact on affecting the health of livestock which in turn will have a direct result in decreased production. Goats that experience worms will experience a lack of nutrition or nutrition, so that their resistance to disease will decrease, so they are prone to other diseases, especially infectious diseases. Bayesian probability theory is a branch of the mathematical-statistical theory that allows us to create a model of the uncertainty of an event that occurs by combining general knowledge with facts from observations.