[Abstract] Objective To investigate the outcomes of non-obstructive azoospermia (NOA) patients with different etiologies undergoing micro-TESE. Methods A retrospective analysis of 1355 patients who accepted micro-TESE in Shanghai General Hospital from March 2015 to January 2022. The etiology/risk factors of NOA patients included Klinefelter syndrome (KS), Y-chromosome AZFc deletion, cryptorchidism, mumps orchitis, chemoradiotherapy, varicocele, idiopathic etiology. The clinical characteristics, sperm retrieval rate (SRR) of patients in each group were compared, and the factors affecting the outcome of sperm retrieval were analyzed successively. Results The overall SRR is 26.2% (355/1355). The mumps orchitis group ranks the highest SRR of 75.9% (22/29), followed by cryptorchidism (70.5%, 43/61), Y-chromosome AZFc deletion (55.6%, 30/54), KS (47.6%, 71/149), idiopathic etiology (18.6%, 167/897), radiotherapy and chemotherapy (15.4%, 2/13), and varicocele was the lowest (13.2%, 20/152). According to the clinical outcome, NOA patients were divided into a success group and a failure group. In idiopathic and chemoradiotherapy group, the levels of FSH and LH in successful cases were significantly higher than those failed; in Y-chromosome AZFc deletion group, the levels of FSH was significantly lower than those failed; in mumps orchitis group, the volume of the testis in the success group was higher than those failed. In addition, we found that age can serve as an independent factor to predict sperm retrieval outcome in patients with idiopathic NOA, and the older had better sperm retrieval outcomes. Conclusion In NOA patients, the SRR of different etiologies/risk factors is significantly different, which is an important prognostic indicator affecting sperm retrieval outcome. In patients with idiopathic NOA, age has a certain predictive value for clinical outcome.