Objective To analyze the relationship between thyroid function abnormality immune-related adverse events (TFA-irAEs) and prognosis outcomes of immunotherapy efficacy in patients with advanced gastric cancer based on Logistic regression analysis. Methods 106 patients with advanced gastric cancer who received treatment with programmed death receptor-1 (PD-1) or programmed death ligand 1 (PD-L1) inhibitor in hospital from March 2020 to March 2022 were selected and divided into TFA-irAEs group and non-TFA-irAEs group according to whether TFA-irAEs occurred during treatment. The clinical features of the two groups were compared, and the risk factors affecting TFA-irAEs in patients with advanced gastric cancer were analyzed based on Logistic regression analysis, and the progression-free survival(PFS) and overall survival (OS) were compared between the two groups.Results Among 106 patients with advanced gastric cancer, 33 cases developed TFA-irAEs after treatment, with the incidence rate of 31.13%. The baseline TSH level and initial TPOAb/TgAb positive rate in TFA-irAEs group were significantly higher than those in non-TFA-irAEs group (P<0.05). Multivariate Logistic regression analysis showed that baseline TSH level and positive initial TPOAb/TgAb were risk factors for TFA-irAEs occurrence inpatients with advanced gastric cancer(P<0.05). ROC diagnostic curve results showed that with 2.16mIU/L as the best cut-off value, the sensitivity and specificity of baseline TSH in predicting TFA-irAEs in patients with advanced gastric cancer were 78.80% and 75.30%, and AUC was 0.703 (95%CI:0.596-0.810). Kaplan-Meier survival curve showed that the median PFS and median OS in TFA-irAEs group were significantly longer than those in non-TFA-irAEs group (Log-rank χ2=13.651, P<0.001; Log-rank χ2=5.149, P=0.023). Conclusion Baseline TSH level and positive initial TPOAb/TgAb are risk factors for TFA-irAEs in patients with advanced gastric cancer, and TFA-irAEs is associated with good prognosis outcomes of immunotherapy efficacy in patients with advanced gastric cancer