Objective To observe the clinical value of multi-slice spiral CT in preoperative diagnosis of gastrointestinal stromal tumor (GIST). Methods 64 patients with GIST in our hospital were detected by TOSHIBA Aquilion 16 slice spiral CT. CT plain scan and three phase enhanced scan were performed. The results were input to ADW4.2 workstation for reconstruction. The images were analysised by 2 senior doctors of the imaging department in our hospital. The results of multi-slice spiral CT scan of the 64 patients were analyzed. Results Among 64 patients with GIST, there were 41 cases of stomach, 15 cases of small intestine, 3 cases of rectum, 3 cases of esophagus and 2 cases of omentum. Shape: quasicircular or oval in 51 cases, irregular lobulated in 13 cases. Distribution: 42 cases in external gastrointestinal tract, 15 cases in internal gastrointestinal tract and 7 cases in internal and external gastrointestinal tract. Mucosal status: smooth mucosa in 41 cases, mucosa with obvious ulcer in 23 cases, cystic solid in 49 cases and solid in 15 cases. Density: compared plain scan and liver parenchyma, the homogeneous density was basically in accordance in 29 cases, equal dencity around and lower inside in 31 cases, gaseous density in 4 cases, without calcification. Enhanced CT scan showed tumors with homogeneous enhancement in 33 cases and inhomogeneous enhancement in 31 cases. In patients with homogeneous enhancement, 31 cases were benign and 2 cases were potentially malignant. In patients with inhomogeneous enhancement, 1 cases were benign, 11 cases were potentially malignant and 19 cases were malignant. Conclusion Multi slice spiral CT in the diagnosis of gastrointestinal stromal tumor can accurately identify the benign and malignant tumors, which can provide objective basis for the preoperative pathological diagnosis and choice of surgery.