Objective：To investigate the outcomes of non - obstructive azoospermia(NOA) patients with different etiologies undergoing microdissection testicular sperm extraction(micro - TESE). Methods：A retrospective analysis was carried out in 1 355 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 sperm retrieval rate(SRR)of patients in each group were analyzed，and the pregnancy outcomes of successful sperm retrieval in each group were compared. Results：The overall SRR was 26.2%(355/1 355). The mumps orchitis group ranked 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 follicle-stimulating hormone(FSH)and luteinizing hormone(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. After ICSI treatment，the pregnancy rate was 51.4%(200/389)，and the live birth rate was 73.5%(147/200). Conclusion：The SRR of NOA patients with different causes/risk factors are significantly different，which are important indicators affecting the outcome of micro-TESE.