Diarrhea after appendicitis surgery is usually due to the following reasons: gastrointestinal dysfunction, inflammation stimulation, intestinal flora imbalance, and so on. 1. Gastrointestinal dysfunction: after appendicitis surgery, due to inflammation in the abdominal cavity, it may lead to gastrointestinal dysfunction, and the digestive tract’s ability to digest and absorb food will be reduced, which may lead to diarrhea. 2. Inflammatory stimulation: If appendicitis is relatively heavy, after surgery, there will be residual inflammation in the abdominal cavity, and even lead to pelvic effusion, which will stimulate the rectal peristalsis to accelerate, and may lead to the phenomenon of diarrhea. 3. Intestinal flora imbalance: After appendicitis surgery, antibiotics need to be applied, which may lead to intestinal flora imbalance, if there is intestinal flora imbalance, it will lead to diarrhea. It is necessary to improve the relevant examination, such as abdominal ultrasound, stool routine, etc., usually can clarify the cause, and then can be treated accordingly.