Appendicitis fever is related to bacterial infection, and if the temperature reaches 39~40℃, appendiceal perforation is also considered. 1. Bacterial infection: appendicitis is an inflammation of the appendix due to blockage of the lumen of the appendix caused by various reasons and secondary bacterial infection. Appendicitis fever is more common in acute appendicitis, the appendix and the colon are connected, the distal end is the cecum, if the appendix appears to be blocked, it will lead to a large number of bacterial reproduction, and then there will be symptoms of fever. 2. Perforated appendix: appendicitis is not timely treatment, will form a perforation, appendicitis perforation, a large number of bacteria will be absorbed by the peritoneum and mesentery into the blood circulation sepsis, then the body temperature will be further increased to 39 ~ 40 ℃, will pose a certain threat to the life, it should be rescued in a timely manner. Whether it is acute appendicitis or chronic appendicitis, once the diagnosis is made, surgery should be carried out as soon as possible to remove the appendix, and take care of rest after the operation.