Objective To investigate the correlation between preoperative prognostic nutritional index PNI and skeletal muscle area SMA and prognosis of patients with gastric cancer after total gastrectomy. Method A total of 109 patients with gastric cancer who received total gastectomy in the Affiliated Hospital of Jianghan University / Wuhan Sixth Hospital from March 2019 to December 2020 and were followed up to December 2023 were selected as the study subjects and set as the gastric cancer group and 54 healthy subjects were selected as the healthy control group. The changes of PNI and SMA between the two groups were compared. The expressions of PNI and SMA in different pathological features of gastric cancer patients were observed. Spearman method was used to analyze the correlation between PNI SMA and clinical features of gastric cancer patients. Cox proportional risk model was used to analyze the effects of PNI and SMA on 3 - year progression - free survival and overall survival of gastric cancer patients. Receiver operating characteristic ROC curve were drawn to analyze the area under the curve AUC sensitivity and specificity of SMA in predicting the prognosis of patients with gastric cancer. Result PNI and SMA in gastric cancer group were lower than those in healthy control group P<0. 05 . The PNI and SMA of gastric cancer patients with stage Ⅲ low differentiation T3-T4 infiltration lymph node metastasis and vascular invasion were lower than those with stage Ⅰ to Ⅱ medium to high differentiation T1-T2 infiltration and no lymph node metastasis and vascular invasion P < 0. 05 . Correlation analysis showed that PNI and SMA were negatively correlated with clinical stage differentiation degree depth of invasion lymph node metastasis and vascular invasion P<0. 05 . Cox proportional risk model multivariate analysis showed that the decrease of SMA was an independent factor for 3-year progression-free survival in patients with total gastrectomy for gastric cancer P< 0. 05 . ROC curve analysis showed that the AUC sensitivity and specificity of SMA in predicting 3 -year progression -free survival of patients with total gastrectomy for gastric cancer were 0. 797 69. 90% and 83. 30% respectively. Conclusion PNI and SMA showed a significant downward trend in gastric cancer patients and their levels changed with the severity of the patient 's disease and affected the prognosis. Dynamic detection of their changes was conducive to providing guidance for clinical treatment and prognosis assessment. Decreased SMA was an independent factor for 3-year progression-free survival in patients with total gastrectomy for gastric cancer