Abstract: The polymorphisms of exon 2 and exon 3 in the SLA-DMA gene were studied based on the PCR-SSCP patterns and the sequences in Ganzi Tibetan pigs (T), Hezuo pigs (HZ), Bama pigs(BM) and Wuzhishan pigs(WZS), no allelic variation was recognized in the second exon, but two allelic variations were recognized in the third exon in four different miniature breeds of swine. By optimizing a low ionic strength solution (LIS) PCR-SSCP, cloning sequencing, bacterical colony PCR, asymmetric PCR and structure prediction of DNA single-strand, the complicated patterns about allele K and J based on PCR-SSCP in the exon 3 were confirmed. There was highly identity comparing the pattern of allele J with the predicted second structure of DNA single-strand. The frequencies of three kinds of genotypes JJ, JK, KK in the third exon of SLADMA gene were fit with Hardy-Weinberg equilibrium in four populations. The frequency of allele K was higher than that of allele J. Values of the heterozygosity and the polymorphism information contents in the exon 3 of SLA-DMA gene were showed low polymorphism in T, but moderate polymorphisms in BM, WZS,and HZ.