Abstract To investigate the pattern of genetic variation of inbred line Ⅰ of Wuzhishan mini-pig(WZSP)(Sus scrofa) from the 19th to the 21th generations, fifty-three individuals of the inbred line Ⅰand 14 microsatellite loci were used to estimate their genetic heterozygosity(H), polymorphic information content (PIC) and number alleles(N). The results showed that there were a total of 28 alleles at the 14 loci, and the number of allele on F19, F20 and F21 groups were 28, 26 and 24, respectively; average loci alleles were 2.00, 1.86 and 1.70, respectively. In addition，the average PIC and H were 0.24 and 0.31, respectively, which were lower than that of F18 generation; among them, five loci had reached the fully homozygous at the 19th generation as well as did Sw1377 at the 21th generation. But there were a few loci high heterozygosity(H), such as Sw902, S0036 and Sw874. It was speculated that these genes may be related to maintain its a trait in the WZSP. The results of this study are used to provide the basis on inbred line nurture in large animal
