Abstract: Objective To explore the effect of small interfering RNA (siRNA)-mediated CEP55 gene silencing on the proliferation of mouse spermatogonia. Methods Six patients with azoospermia diagnosed to have maturation arrest (3 cases) or normal spermatogenesis (3 cases) based on testicular biopsy between January 1 and December 31, 2017 in our center were examined for differential proteins in the testicular tissue using isobaric tags for relative and absolute quantitation (iTRAQ), and CEP55 was found to differentially expressed between the two groups of patients. We constructed a CEP55 siRNA for transfection in mouse spermatogonia and examined the inhibitory effects on CEP55 expressions using Western blotting and qPCR. The effect of CEP55 gene silencing on the proliferation of mouse spermatogonia was evaluated with CCK8 assay. Results In the testicular tissues from the 6 patients with azoospermia, iTRAQ combined with LC/MS/MS analysis identified over two hundred differentially expressed proteins, among which CEP55 showed the most significant differential expression between the patients with maturation arrest and those with normal spermatogenesis. The cell transfection experiment showed that compared with the cells transfected with the vehicle or the negative control sequence, the mouse spermatogonia transfected with CEP55 siRNA showed significantly lowered expressions of CEP55 mRNA and protein (P<0.05) and significantly decreased proliferation rate as shown by CCK8 assay (P<0.05). Conclusion CEP55 may play a key role in spermatogenesis and may serve as a potential therapeutic target for non-obstructive azoospermia with maturation arrest.