Objective: To study the clinical application value of preoperative ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in prognostic assessment of non-small cell lung cancer (NSCLC). Methods: Eighty-five patients with stage III squamous cell carcinoma who underwent radical NSCLC surgery in our hospital from January 2015 to January 2017 were retrospectively selected as the research subjects. According to ¹⁸F-FDG PET-CT data of patients, the maximum standard uptake value (SUVmax), tumor metabolic volume (MTV) and tumor total glycolysis (TLG) of patients with primary lung lesions were recorded. The optimal critical values of SUVmax, MTV and TLG for predicting the total survival time (OS) of patients were obtained by using the receiver operating characteristic (ROC) curve. Statistically significant indexes were screened to analyze whether there was any relationship between SUVmax, MTV and TLG and clinicopathological features. According to the critical values, the differences of OS among each group were compared, and the risk factors affecting prognosis were analyzed. Results: The results of ROC analysis showed that SUVmax had a higher value in predicting OS (P<0.05), while MTV and TLG had a lower predictive value (P>0.05). When the critical value of SUVmax was 9.09, the maximum Youden index was 0.73. SUVmax had no significant relationship with age, gender, tumor diameter, pathological type and tumor differentiation degree (P>0.05). Univariate analysis showed that tumor diameter ≥3 cm, tumor differentiation, high SUVmax, high MTV and high TLG were all influencing factors of OS in patients (P<0.05). COX regression analysis showed that high SUVmax was an independent risk factor affecting the survival time of patients (P<0.05). Conclusion: SUVmax of the primary lesion in ¹⁸F-FDG PET-CT imaging before radical NSCLC surgery has important clinical value in predicting the postoperative survival time of patients.