This multicenter, prospective randomized controlled study is designed to applicate perioperative Enhanced recovery after surgery (ERAS) management for children with acute complicated appendicitis, the aim is to promote postoperative recovery, shorten the hospital length of stay, and reduce the incidence of postoperative complications.

The purpose of this study is through multi-center prospective RCT research, to discuss the application of ERAS in children with acute complicated appendicitis, including its preoperative rehydration, postoperative analgesia, preoperative and postoperative antibiotics application, as well as the discharge standards and so on. The major outcome is whether it can reduce the length of stay in hospital (LOS), secondary outcomes are included the incidence of postoperative complications and postoperative readmission rate, etc.

Inclusion Criteria:

• ages<14; no gender limitation;
• Alvarado scores ≥7;
• preoperative radiography examination indicated complicated appendicitis;
• Patients or their legal representatives have signed "informed consent"

Exclusion Criteria:

• complicated life-threatening disease;
• perioperative exploration not appendicitis;
• Recently participated in other clinical trials within 3 months;
• Researchers found not fit to participate in this trial for any condition

De-identified individual participant data for all primary and secondary outcome measures will be made available.