Background: Gastroesophageal Junction neuroendocrine neoplasms (GEJ-NENs) are rare and heterogeneous tumors. We aim to analyze the clinicopathlogical features and prognostic factors of GEJ-NENs and to compare the outcome of GEJ-NENs with other gastric NENs. Methods: A total of 297 GET-NENs patients were enrolled from 10 Chinese hospitals and 3152 gastric NENs patients, including 274 GEJ-NENs, were retrieved from Surveillance, Epidemiology, and End Results (SEER) database. Results: The clinical characteristics of GEJ-NENs among different races were different. All Chinese patients had GEJ-NENs of grade 3, with 67.7% of poorly differentiated NEC and 32.3% of MANEC. In SEER database, 70.8% of white, 62.5% of black, and 87.5% of AP patients had poorly differentiated/undifferentiated tumors. In Cox multivariate analysis, NEC/MANEC (HR 2.09, 95%CI 1.24-3.56; P = 0.006), lymph node metastasis (HR 3.52, 95%CI 1.68-7.34; P = 0.001), and distant metastases (HR 3.90, 95%CI 2.50-6.08; P < 0.001) are independent predictors of overall survival. Surgical resection showed a median OS improvement of 13.1-73.3 months (HR 0.21, 95% CI 0.14-0.33, P < 0.001). Adjuvant therapy did not improve survival for postoperative GEJ-NEN patients (P = 0.141). GEJ-NENs were larger, higher grade, more distant metastasis, and worse prognosis than other gastric NENs. Conclusion: GEJ-NENs were mostly poorly differentiated carcinomas, and all of Chinese patients were NEC/MANEC. The outcome of MANEC was preferable to NECs. Both lymph nodes metastasis and distant disease were independent predictors of prognosis. Surgical resection can improve survival, but postoperative adjuvant therapy had no additional benefit. GEJ-NENs have worse survival than other gastric NENs.