Background and Aims The disease burden of gastric cancer in China is high and there are many prognostic factors. There are few studies on the quantitative and comprehensive assessment of prognostic risk. Therefore, this study explored the significance of inflammatory indicators neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) on the prognosis and survival of gastric cancer patients based on nomogram and included them in nomogram and traditional TNM staging to compare the prognostic evaluation efficacy.Methods A retrospective study was conducted in the Department of Gastrointestinal Surgery of the First Affiliated Hospital of University of Science and Technology of China from June 2013 to June 2018. Gastric cancer patients who underwent radical gastrectomy were included in the training group (n=300). Patients with the same diagnosis who experienced the same surgical treatment from another ward were included as the validation group (n=100). The patient's age, gender, tumor type, tumor site, invasion depth, and lymph node metastasis (LNM) were collected through the hospital's electronic medical record system. Peripheral venous blood data were collected 3 days before the operation, and NLR and PLR were calculated. The ROC curve determined the optimal critical points of NLR (1.98) and PLR (134.87). The patients were followed up every 3 months within 2 years and every 6 months after 2 years. Cox proportional hazards model was used to calculate the association between exposure and outcome indicators, and the independent risk factors affecting the prognosis of gastric cancer were identified according to the results of multivariate analysis. The stability of the nomogram was evaluated by C-index in the training group and the validation group after inclusion in the nomogram. Finally, the prediction performance of nomogram and traditional TNM staging was compared based on the area under the ROC curve (AUC).Results There were 220 male patients (73.3%) in the training group and 69 male patients (69.0%) in the validation group. The average age of the training and validation groups was (62.52±10.61) years and (63.67±10.21) years, respectively. There was no significant difference in other baseline characteristics between the two groups except tumor type, differentiation degree and invasion depth. The training group's median overall survival (OS) was 28 months, and the 1-year, 3-year and 5-year OS rates were 63.9%, 43.1% and 35.1%, respectively. The median OS in the validation group was 32 months, and the 1-year, 3-year and 5-year OS rates were 58.9%, 41.6% and 31.7%, respectively. Univariate Cox regression analysis showed that age, pathological type, degree of tumor differentiation, depth of invasion, LNM, NLR, PLR and CEA levels were all associated with OS (all P<0.05). After multivariate adjustment, patients with LNM, preoperative NLR>1.98, PLR >134.87 and carcinoembryonic antigen (CEA) ≥5 μg/L had significantly shorter OS (all P<0.01). The calibration curve results showed that the nomogram model fits well in the training group (C-index=0.81) and the validation group (C-index=0.75). In addition, the AUC values of the nomogram model in predicting the 1-year, 3-year, and 5-year OS rates of the training group (0.865, 0.855, 0.827) were higher than those of the TNM stage (0.677, 0.690, 0.683). The AUC values of 1-year, 3-year, and 5-year OS rates in the training group (0.856, 0.788, 0.725) were higher than those of the TNM stage (0.781, 0.691, 0.605).Conclusion NLR and PLR are independent risk factors for predicting the survival of patients with gastric cancer. The constructed nomogram could more accurately predict the 1-, 3-, and 5-year OS rates of gastric cancer patients undergoing gastrectomy and provide clinicians with more accurate treatment and nursing decision-making evidence.