Abstract： Objective To analyze the rationality of 16 or more multi-slice helical CT (MSCT) utilization for solitary pulmonary nodule (SPN) (<3 cm). Methods One hundred and fifty consultant cases with SPN from 133 different hospitals, examined with 16 or more MSCT, were selected in this study. The reconstructed slice thickness of routine CT scan, thin slice reconstruction thickness, 2D or 3D reconstruction, window wide and level setting, contrast enhancement effect were recorded from consultant films. Thoracic CT scan criteria for SPN were proposed according to the scan guidelines at Stanford University and PubMed articles. The rationality of 16 or more MSCT utilization in other hospitals for SPN was analyzed by two radiologists compared with scan criteria. The diagnostic accuracy in other hospitals was evaluated according to the pathologic and treatment results in our hospital. Results Sixteen-MSCT was performed in 92 cases, 64-MSCT in 54 cases and 40-MSCT in 4 cases. In routine thoracic CT scan, 9--10 mm reconstructed slice thickness was selected in 59 cases, 7--8 mm thickness in 12 cases and 5 mmthickness in 79 cases. Consecutive thin slice thickness (<3 mm) was used for SPN only in 46 cases. OnlyMPR and VR were filmed in 9 cases without thin slice reconstructed axial images. :53 cases (35.3%) were rescanned in our hospital due to the unsatisfied image quality. Of 150 cases, 78 cases had pathologic or treatment results in our hospital and 22 cases (14.7%) were proved to be misdiagnosed in other hospitals, and only 2 cases were misdiagnosed in our hospital. Conclusion There are many irrationalities of 16 or more MSCT utilization in our country which influence the diagnostic accuracy of SPN, Unified thoracic CT scan criteria in our country are needed.