Abstract: To assess the level and pattern of genetic variation of three inbred families of Wuzhishan Miniature pig (WZSP) from the 13^th to the 18^th generations， 14 microsatellite DNA markers were used to estimate their genetic heterozygosity (H)， polymorphic information content (PIC) and number of alleles (N).The results showed that there were a total of 38 alleles at the 14 loci and the estimates of average H， PIC and N in the pooled samples were 0.42， 0.37 and 2.71， respectively. The average H and N in three families ranged from 0.41 to 0.45， and from 2.29 to 2.50， respectively. In addition， the average H and N from the 13th to the 18th generations were 0.31， 0.42， 0.36， 0.41， 0.37 and 0.20， and 2.21， 2.57， 2.43， 2.57， 2.36 and 1.64， respectively. It was noted that three microsatellites （Sw71， Sw510 and Sw2409） had been fixed in all three families at the 13^th generation， however， some loci like Sw205， Sw874 and Sw936 among others still demonstrated high levels of heterozygosity， though very low N from 2 to 4， in all three families across all generations. In conclusion， this study revealed the pattern of genetic variation at microsatellite loci in the inbred families of WZSP with one of the most important findings to be the high level of unexpected heterozygosity at some loci， e.g. Sw874 and Sw936 that could be part of the unique genetics of these families. Whether functional genes linked with such microsatellite loci were involved in the maintenance of viability of these inbred families of WZSP remains for further investigation.