Objective To explore the clinical characteristics and causes of misdiagnosis of primary small intestinal tumors.Methods 54 cases of primary small intestinal tumors were retrospectively analyzed.Results Among them,32 of 54 cases were misdiagnosed for 2 to 16 months.Preoperative misdiagnosis rate was 59%.In this group,11 cases were benign tumors while the other 21 cases were malignant tumors located at duodenum jejunum and ileum were found in 7 cases,13 cases and 12 cases respectively.The most common clinical presentations were abdominal pain,abdomen mass,gastrointestinal haemorrhage and jaundice,etc.The accurate diagnosis rate of whole digestive tract radiography and CT scanning was lower,while small radiography of hypotonic and CTVE and MRVE and DSA was helpful to make sure the portion and quality of the lesion.Conclusion The reasons of misdiagnosis are following:insufficient understanding about the disease,the clinical presentation of primary small intestinal tumor is untypical prognosis of these patients.