It is well known that acute appendicitis is the most common abdominal emergency in adult surgery. In fact, pediatric acute appendicitis is also the most common disease in pediatric abdominal surgery. However, unlike adults, pediatric acute appendicitis, especially in infants and children under 3 years of age, is rapidly progressive and easily misdiagnosed, often resulting in serious consequences for the child, which is very distressing! The clinical symptoms of appendicitis in infants and children are very atypical and the lesions develop rapidly, with septic perforation and diffuse peritonitis occurring within a few hours. Due to the inability of the child to express the condition clearly and the lack of cooperation in abdominal examination, early appendicitis is often clinically misdiagnosed as indigestion and epiglottitis. In addition, infants and children with inadequate development of the greater omentum cannot confine abdominal inflammation and further form multiple abdominal abscesses (e.g., pelvic abscess, subdiaphragmatic abscess, and intestinal interstitial abscess). The inflammation and pus stimulation in the abdominal cavity soon form severe intestinal adhesions and lead to adhesive intestinal obstruction. Some of them even cause infectious shock and endanger the life of the child. The etiology of pediatric appendicitis is multifaceted and is related to anatomical factors, infection, and immune deficiency. The appendiceal cavity is small in children and the appendix is a blind tube, which can easily drain poorly and form fecal stones. In some children, the appendix itself is narrowed or has congenital distortions that predispose them to appendicitis. Sometimes foreign bodies such as parasites, roundworms and pinworm eggs can block the lumen of the appendix and lead to appendiceal necrosis and perforation. In addition, bacteria can infiltrate the appendiceal wall and produce acute inflammation when the mucosa is damaged. Bacteria can also enter the appendix through the bloodstream from other inflammatory sites such as upper respiratory tract infections. The appendix is rich in submucosal lymphatic tissue, and bacteria in the bloodstream are not filtered and remain in the lymphatic tissue within the appendiceal wall to produce acute appendicitis. The common bacteria that cause appendicitis in children are Staphylococcus aureus, Escherichia coli, Streptococcus, Enterococcus, or anaerobic bacteria. Because of the rapid onset and progression of appendicitis in infants and children, diffuse peritonitis, abdominal abscesses, intestinal adhesions, and even sepsis and infectious shock often develop quickly. When pediatric appendicitis comes to the clinic, serious complications are often already present, making treatment difficult. Families of children often consider appendicitis to be a minor illness, and doctor-patient disputes often occur over it. Therefore, when a child has unexplained crying, fever, or vomiting, it is important to be alert to the occurrence of appendicitis. The doctor should carefully examine the child’s abdomen and, if necessary, appropriately sedate the child to sleep before palpating the abdomen. ultrasound can be helpful in the diagnosis of appendicitis, and an experienced ultrasound doctor will find a thickened appendix diameter (greater than 8 mm), a fecal stone in the appendiceal cavity, or an abscess or non-homogeneous mass in the right lower abdomen can help in the diagnosis. Therefore, pediatric appendicitis tries to achieve early diagnosis and early surgery to avoid serious consequences of delayed diagnosis.