Pneumoperitoneum represents the perforation of intraperitoneal hollow organs in most cases. Pneumoperitoneum resulting from a ruptured pyogenic liver abscess is rare. Open drainage followed by antibiotics is recommended for a ruptured pyogenic liver abscess with generalized peritonitis. Herein, we reported a case of pneumoperitoneum resulting from a ruptured pyogenic liver abscess successfully treated by open drainage in a 62-year-old female with diabetes.