Thirteen plasma proteins（enzymes） polymorphism were examined in 28 samples of "Songliao black" pig by means of PAGE in this study.The results showed that Alb, Pa₂ and Cp were monomorphic, while Pa₁, Po₁, Po₂, Tf, Ptf, Akp, Hpx, Am₁, Am₂, Es were polymorphic.These loci had alleles from two to four respectively.The results of Chisquare test showed that Pa₁, Pa₂, Ptf, Akp were not in Hardy-weinberg balance while Po₁, Po₂, Tf, Am₁, Am₂, Hpx, Es were in Hardy-weinberg balance.The mean number of effective alleles, mean heterozygosity and homogeneity index were 2.0779, 0.5083 and 0.1288 respectively.