PRDM9(PR domain containing 9) is one kind of histone trimethylase which catalyzes the H3K4 trimethylation, and possesses the activity of transcription factor. PRDM9 transcripts were only expressed in germ cells entering meiotic prophase in female fetal gonads and in postnatal testis, whose deficiency results in sterility. The zinc finger motif of mammalian PRDM9 rapidly evolves, which is respond to the sequences of recombination hotspots. Several researches indicated that PRDM9 was involved in the binding to recombination hotspots and initiation of recombination. These progresses are important for understanding of species evolution and the mechanism of genetic recombination.