A novel microsatellite DNA was isolated from a single porcine PAC clone by sequencing the PAC clone directly with (CA)n repeat motif anchored primer. The specific primer pairs flanking the (CA)n repeat region were used to amplify the genomic DNA of 40 individuals from 8 pig breeds, which detected three alleles with the fragment length of 305 bp, 307 bp and 309 bp. The PCR product sequencing results of homozygous animals representing three alleles revealed that those three alleles contained 12,13 and 14 CA dinucleotide repeats respectively.