Objective To discuss the CT and MRI features of gastrointestinal stromal tumor(GIST) and analyse the reasons of missed diagnosis and misdiagnosis. Methods The CT and MRI imaging of 20 cases with GIST proved by pathology were retrospectively analyzed, of which 15 cases and 5 cases underwent CT and MRI respectively. Results 19 cases had solitary masses (12 in stomach, 2 in small intestine, 3 in colon and 2 in mesentery), Multiple was 2 case which were found in mesocolon pelvinum and jejunum. They were round or oval shapes from 3 to 10 cm with clear boundary, growth intraluminal, exophytic or dumbbell. With CT non-enhanced scan, the tumors were non-homogeneous texture with cystic or necrotic changes, some of them could see “Torri-celli-Bernoulli" sign. With MRI, the tumors appeared as heterogeneous hypointensity on T1WI, heterogeneous hyperintensity on T2WI and hyperintensity on DWI. With contrast enhanced scan. The parenchyma of tumors were intensified and enhancement was more obvious in the venous phase than in the arterial. 2cases were missed diagnosis which in the body of stomach. 3 cases were misdiagnosis, which 2 cases as cystadenocarcinoma and 1 case as rectal carcinoma. Conclusion The location of GIST is changeable. Adequate bowel preparation and master of their CT and MRI features, which are helpful to avoid missed diagnosis and misdiagnosis.