A 43-year-old male with a diagnosis of severe acute pancreatitis (SAP) was admitted to our hospital. After receiving the step-up approach for three weeks, the patient had a sudden hematemesis (nearly 400 ml). Gastroscopy and computed tomography (CT) were performed on the same day, revealing a gastric ulcer with a hemorrhage and the portal vein was extremely compressed by peripancreatic fluid collections in the retroperitoneal space.