Arginine methylation is one of the most important post-translational modifications which is catalyzed by protein arginine methyltransferases (PRMTs). Previous studies have demonstrated that Prmt5 plays important role in germ cell development. Prmt7 is the only family member responsible for mono-methylation of arginine residue. However, whether Prmt7 is also involved in germ cell development remains unclear. In this study, we find that PRMT7 is abundantly expressed in the male germ cells during embryonic stage (from E10.5). Depletion of Prmt7 results in the defect of germ cell proliferation during embryonic stage and the number of primordial germ cells is significantly reduced in Prmt7(-/-) mice at E11.5. We also find that the size of testes is reduced in Prmt7(-/-) mice at P5 with reduced germ cell number and the diameter of seminiferous tubules. Further study reveals that the expression of BMPs and TGF-beta singling pathway is significantly changed in germ cells of Prmt7(-/-) mice at E12.5. However, no defect of testes development is observed in adult Prmt7(-/flox); Mvh-Cre mice. Collectively, this study demonstrates that Prmt7 plays roles in male germ cell proliferation during embryonic stages and it is not required for germ cell development postnatally. (C) 2020 Elsevier Inc. All rights reserved.