Abstract: Intestinal obstruction caused by primary intraperitoneal hernia is infrequent and difficult to diagnose. Incorrect diagnosis and delayed surgical treatment will lead to serious consequences. We report a rare case of a 62-year-old Chinese woman with strangulated lesser omentum hiatus hernia. Contrast-enhanced abdominal computed tomography(CT) scan is recommended for early revealing direct and indirect signs. We propose three diagnostic points of primary intraperitoneal hernia: 1. "Three-no" pathography: with no history of abdominal operation, abdominal trauma and abdominal infection. 2. It begins with mechanical intestinal obstruction, then turns into strangulated intestinal obstruction easily. 3. Exclude intestinal wall lesions and intestinal blockage. We also summarize surgical procedure into four steps. We hope this case can provide a reference for the diagnosis and treatment of similar situations.