Objective To explore the mutation of Y-STR loci in meiotic allelic transmission in a large pedigree. Methods The oral swabs of 163 male individuals were collected froma L in pedigree. Twenty-two Y-STR genetic markers were typed with AGCUY 24 fluorescent detection kit (AGCUY 24 sys-tem), which also contained 16 Y-STR markers included in Y filerTmmultiple amplification kit (Y filer system). The genotyping results of Y-STR loci were compared between each two males in the pedigree. Results There were 20 and 30 kinds of haplotypes obtained with Y filer and AGCUY 24 systems in 163 male individuals fromthe L in pedigree, respectively. The rates referred to haplotype differences (RRHD) of these two typing systems between male pairs were 0.910 5 and 0.922 7, respectively. The average number of marker differences were 6.582 1 and 9.824 8, respectively. The RRHDincreased along with the incidents of meiosis. Conclusion Y-STR mutation leads to different Y-STR haplotypes among the male members in a paternal pedigree and the rate of difference increases along with the incidents of meiosis.