Objective To observe the application of multi-slice CT volume scan combined with three-dimensional reconstruction in the qualitative identification of solitary pulmonary nodules， in order to provide scientific reference for the diagnosis and treatment of clinically isolated pulmonary nodule disease.Methods Retrospective analysis was conducted to collect the baseline data of 180 patients with solitary pulmonary nodules treated from June 2019 to June 2021.All patients in the group were examined by multi-layer CT volume scan and 3D reconstruction technology. The effectiveness of multi-slice CT volume scan combined with 3D reconstruction technology in qualitative diagnosis of solitary pulmonary nodules was compared with that of pathological examination as gold standard.Results 180 patients with isolated pulmonary nodules were diagnosed by pathological tissue， with a benign rate of 78.89% and a malignant rate of 21.11%. Compared with the benign group， patients in the malignant group had higher blood volume， peak enhancement， and surface permeability levels and shorter peak perfusion times， with statistically significant differences (P<0.05). The level of multilayer CT volume scan parameters was used as a test variable， and the nature of isolated pulmonary nodules was used as a optimal threshold was used as the cutoff value for qualitative diagnosis， and multilayer CT volume scan was used to diagnose 145 benign isolated pulmonary nodules and 35 malignant isolated pulmonary nodules， using pathological findings as the gold standard. The K value of multilayer CT volume scan in the qualitative diagnosis of isolated pulmonary nodules was 0.811 (P<0.001). 180 patients with isolated pulmonary nodules were enrolled and detected by 3D reconstruction technology， of which 80.00% were diagnosed with benign isolated pulmonary nodules and 20.00% with malignant， using pathological results as the gold standard， and the K value of multilayer CT volume scan in the qualitative diagnosis of isolated pulmonary nodules was 0.660(P<0.001). When 180 patients with isolated pulmonary nodules were detected by the combined diagnostic test， the detection rate of malignant isolated pulmonary nodules was 20.56% and the detection rate of benign nodules was 79.44%， and the K value of multilayer CT volume scanning combined with 3D reconstruction technique in the qualitative diagnosis of isolated pulmonary nodules， using pathological results as the gold standard， was 0.819 (P<0.001).Conclusion The multi-slice CT volume scan and three-dimensional reconstruction technique are of great significance for the qualitative diagnosis of solitary pulmonary nodules， and the combination of the two is the best.