Objective: To explore the clinicopathological features, treatment strategy and to analysis of prognosis-related risk factors of gastric neuroendocrine neoplasms(G-NEN). Methods: In this study, a retrospective observational study method was used to collect the clinicopathological data of patients diagnosed with G-NEN by pathological examination in the First Medical Center of PLA General Hospital from January 2000 to December 2021. The basic information of the patients, tumor pathological characteristics, and treatment methods were entered, and the treatment information and survival data after discharge were followed up and recorded. The Kaplan-Meier method was used to construct survival curves, and the log-rank test to analyze the differences in survival between groups. Cox Regression model analysis of risk factors affecting the prognosis of G-NEN patients. Results: Among the 501 cases confirmed as G-NEN, 355 were male and 146 were female, and their median age was 59 years. The cohort comprised 130 patients (25.9%) of neuroendocrine tumor (NET) G1, 54 (10.8%) of NET G2, 225 (42.9%) of neuroendocrine carcinoma (NEC), and 102 cases (20.4%) of mixed neuroendocrine-non-neuroendocrine(MiNEN). Patients NET G1 and NET G2 were mainly treated by endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR). The main treatment for patients with NEC/MiNEN was the same as that for gastric malignancies, namely radical gastrectomy+lymph node dissection supplemented with postoperative chemotherapy. There were significant differences in sex, age, maximum tumor diameter, tumor morphology, tumor numbers, tumor location, depth of invasion, lymph node metastasis, distant metastasis, TNM staging and expression of immunohistological markers Syn and CgA among NET, NEC, and MiNEN patients (all P<0.05). Further for NET subgroup analysis, there were significant differences between NET G1 and NET G2 in the maximum tumor diameter, tumor shape and depth of invasion(all P<0.05). 490 patients (490/501, 97.8%) were followed up with a median of 31.2 months. 163 patients had a death during follow-up (NET G1 2, NET G2 1, NEC 114, MiNEN 46). For NET G1, NET G2, NEC and MiNEN patients,the 1-year overall survival rates were 100%, 100%, 80.1% and 86.2%, respectively; the 3-year survival rates were 98.9%, 100%, 43.5% and 55.1%, respectively. The differences were statistically significant (P<0.001). Univariate analysis showed that gender, age, smoking history, alcohol history, tumor pathological grade, tumor morphology, tumor location, tumor size, lymph node metastasis, distant metastasis, and TNM stage were associated with the prognosis of G-NEN patients (all P<0.05). Multivariate analysis showed that age ≥60 years, pathological grade of NEC and MiNEN, distant metastasis, and TNM stage III-IV were independent factors influencing the survival of G-NEN patients (all P<0.05). 63 cases were stage IV at initial diagnosis. 32 of these were treated with surgery and 31 with palliative chemotherapy. Stage IV subgroup analysis showed that the 1-year survival rates were 68.1% and 46.2% in the surgical treatment and palliative chemotherapy groups, respectively, and the 3-year survival rates were 20.9% and 10.3%, respectively; the differences were statistically significant (P=0.016). Conclusions: G-NEN is a heterogeneous group of tumors. Different pathological grades of G-NEN have different clinicopathological features and prognosis. Factors such as age ≥ 60 years old, pathological grade of NEC/MiNEN, distant metastasis, stage III, IV mostly indicate poor prognosis of patients. Therefore, we should improve the ability of early diagnosis and treatment, and pay more attention to patients with advanced age and NEC/MiNEN. Although this study concluded that surgery improves the prognosis of advanced patients more than palliative chemotherapy, the value of surgical treatment for patients with stage IV G-NEN remains controversial.