Abdominal compartment syndrome with increased abdominal pressure resulted in multi-organ dysfunctions can be lethal in children. The open abdomen procedure intentionally leaves the abdominal cavity open in patients with severe abdominal sepsis and abdominal compartment syndrome by temporarily relieving the abdominal pressure. We reported our experience of open abdomen procedure in successfully treating a 4-year old boy with abdominal compartment syndrome caused by severe fungal peritonitis and sepsis after gastric perforation.