Objective To evaluate the dynamic changes of the neutrophil to albumin ratio (NAR) during gastric carcinogenesis and its diagnostic value for gastric cancer. Methods Patients diagnosed with gastritis, gastric intraepithelial neoplasia or gastric cancer at the Department of Gastroenterology in our hospital from October 2018 to July 2022 were included. Laboratory and endoscopic data were collected through the medical record system. Binary logistic regression analysis was used to assess the relationship between NAR and clinicopathological characteristics in patients with different gastric mucosal lesions. The receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic efficacy of NAR for gastric cancer. Results Compared with patients with gastritis or gastric precancerous lesions, patients with gastric cancer had significantly higher NAR levels (P<0. 001). Logistic regression analysis indicated that NAR was independently associated with gastric cancer. ROC curve analysis revealed that the area under the curve (AUC) of NAR for diagnosing gastric cancer was 0. 65 (95% CI:0. 63 ~ 0. 67). Conclusions During the development of gastric cancer, the NAR levels of gastric cancer patient are increased significantly. NAR may be used as a new auxiliary biomarker for the detection of gastric cancer.