Abstract: Objective To evaluate the value of high resolution CT and spiral CT enhanced scanning in diagnosis of small peripheral hung cancer. Methods The authors collected 46 patients with pathologically-proved small peripheral lung cancer (≤3cm in diameter). All cases were scan by high resolution CT. To study the stigmata of all. Spiral CT enhanced scanning was done in 25 patients, Analysis stigmata of the increasing range in CT value in reinforcement anterior and posterio. Results Manifest of high resolution CT scanning:①lobulation sign (91.3%);②spiculatecd sign(87%);③pleural indentation sign (78.3%);④vascularnotch sign (54.3%);⑤sign of air bronchus and vacuole (34.8%);⑥spinose processus (32.65%);⑦milling glass dens (10.9%);⑧calcification (8.7%). The increasing range in CT value in reinforcement anterior and posterio 20~30 HU (16%), 30~65 HU(76%),>65 HU(8%). Conclusion High resolution CT and spiral CT enhanced scanning were important method in the diagnosis of small peripheral lung cancer. The final diagnosis which are of more than 3 sign on CT or above all are 2 sign in anterior 5 sign, precision rate(91.3%). The icereasing range in CT value in reinforcement anterior and posterio 20~30 HU, It is terrier reliable in diagnosis of lung cancer, precision rate (92%).