Object To evaluate the preoperative nutritional status of patients with lung cancer surgery by PNI and NRS 2002, and to compare their effects on prognosis. Methods A total of 172 patients with lung cancer diagnosed from January 2017 to October 2017 in the Department of Thoracic Surgery, Anhui Provincial Hospital, the First Affiliated Hospital of China University of Science and Technology were enrolled. The prognostic nutrition index (PNI) and nutritional risk screening 2002 (NRS 2002) were used to evaluation the preoperative nutritional status of lung cancer patients.The patients were divided into high PNI group and low PNI group with a cutoff point of 48. Nutritional risk screening was performed at admission. Patients with a NRS 2002 total score of ≥3 had a nutritional risk, and those with a score of <3 had no nutritional risk. Results The number of lymph node metastasis,late TNM stage and postoperative complication rates in the low PNI group were higher than in the high PNI group,and the postoperative hospital stay and chest lead time were longer than those in the high PNI group(P<0.05). The incidence of nutritional risk was 16.86%. The late TNM stage,postoperative adjuvant treatment and postoperative complication rates in the nutrition risk group were higher than in the no nutrition risk group,and chest lead time was longer than that in the no nutrition risk group(P<0.05). In terms of specificity of the two nutritional assessment methods in predicting postoperative complications of lung cancer, PNI was higher than NRS 2002 score（85.5% vs 67.5%，P>0.05）. Conclusion The preoperative nutritional status can affect the prognosis of lung cancer patients to some extent. There was no significant difference in predicting the postoperative complications of lung cancer patients, the specificity of PNI was higher than that of NRS 2002. In view of the simplicity and convenience of the two evaluation methods, it has certain clinical application value.