As a core transcriptional factor regulating pluripotency, Krüppel-like factor 4 (KLF4) has gained much attention in the feld of stem cells during the past decades. However, few research have focused on the function of KLF4 during human primordial germ cell (PGC) specifcation. Here, we induced human PGC-like cells (hPGCLCs) from human embryonic stem cells (hESCs) and the derived hPGCLCs upregulated PGC-related genes, like SOX17, BLIMP1, TFAP2C, NANOS3, and the naïve pluripotency gene KLF4. The KLF4-knockout hESCs formed typical multicellular colonies with clear borders, expressed pluripotency genes, such as NANOG, OCT4, and SOX2, and exhibited no diferences in proliferation capacity compared with wild type hESCs. Notably, KLF4 deletion in hESCs did not infuence the induction of PGCLCs in vitro. In contrast, overexpression of KLF4 during PGC induction process inhibited the efciency of PGCLC formation from hESCs in vitro. Overexpression of KLF4 may regenerate the naïve ground state in hESCs and results in repression for PGC specifcation. Thus, KLF4 could be a downstream target of human PGC program and the upregulation of KLF4 is prepared for late stage of germline development.