Objective To explore the correlation between sarcopenia and tumor clinical stage characteristics adverse reactions after chemotherapy and peripheral blood inflammatory indexes. Moreover the correlation between appendicular skeletal mass index ASMI and the patient-generated subjective global assessment PG-SGA for the assessment of patient nutritional status were also be analyzed. Method The clinical data of 125 patients with advanced gastric cancer in the First Affiliated Hospital of University of Science and Technology of China Western District from January 2019 to February 2022 were collected. Pearson analysis was carried out to analyze the correlation between ASMI and PG-SGA score. Result Among the 125 patients the incidence of sarcopenia was 43. 2% 54 of 123 patients . The sarcopenia group was significantly older and the incidence of grade Ⅲ/ Ⅳ adverse reactions after chemotherapy was higher In addition the sarcopenia group showed lower BMI but higher PG-SGA score and NLR neutrophil-to-lymphocyte ratio NLR P <0. 05 . Univariate analysis and multivariate analysis showed that age PG-SGA score grade Ⅲ/ Ⅳ adverse reaction after chemotherapy and NLR were independent risk factors for sarcopenia P < 0. 05 . There was a significant negative correlation between ASMI and PG-SGA score r = - 0. 38 P < 0. 001 . Conclusion Advanced age the occurrence of adverse reactions after chemotherapy and the systemic inflammatory state of patients are closely related to the occurrence of sarcopenia in advanced gastric cancer. ASMI and PG-SGA have a good correlation in the evaluation of nutritional status of patients.