Objectives to explore clinical value of spiral CT in the diagnosis of lung cancer, and to provide reliable basis for clinical treatment for lung cancer. Methods 102 patients with lung cancer admitted by the outpatient service and inpatient department of this hospital were selected as research subjects, all patients were subject to multiple-layer spiral CT, and results of postoperative pathologic histology were compared, the accuracy of diagnosis results was observed. Results According to the comparison in multiple layer spiral CT and pathologic examination results in patients, the detection rate of multiplelayer spiral CT was much higher than that in pathological examination, p<0.05, and the difference was statistically significant. The misdiagnosis rate of multiple-layer spiral CT was significantly lower that that of pathologic examination when compared, p<0.05, and the difference was statistically significant. Conclusions The application of spiral CT derivers extremely important clinical value in the diagnosis of lung cancer, and it can improve the detection rate of lung cancer, but its accuracy is only higher in early diagnosis of lung cancer, and there are certain defects in the diagnosis of lung cancer during later period, thus multiple diagnostic methods have to be combined to conduct diagnose so as to provide reliable basis for clinical treatment of lung cancer.