Hormone sensitive lipase (HSL) is a key enzyme in fat metabolism. The polymorphism of the pig HSL gene is studied in this paper. The SSCP (Single Strand Conformational Polymorphism) is found in the HSL gene Exon 8. It shows three genotypes (MM, MN, NN). Fat-type pig breeds of Meishan and Tongcheng pigs have more allele M, with frequencies of 0.690 M and 0.740 M, respectively; however, lean-type pig breeds of Landrace and the Large White pigs have more allele N, with frequencies of 0.847 N and 0.845 N, respectively. PCR fragments representing HSL genotypes MM and NN are sequenced. Two A-->G transitions are detected, and it resulted in corresponding changes of amino acid (Asn-->Asp and Glu-->Gly) in the HSL protein, respectively. The HSL gene can be considered as a candidate gene for fatness in pigs.