In this paper,the ESTs of pig fat tissue were sequenced and analyzed using the large-scale DNA sequencing method, 7790 high quality ESTs were gained,from which 4354 genes were obtained using cluster analysis with the STACK-PACK software, including 3609 singlet genes and 745 multicopy genes. The 4354 candidate genes were compared with BLASTN to the nr library (e =1e-10), of which 2712 were known genes, containing 1 987 singlet genes and 725 multicopy genes,there are 2 109 unknown genes and new ESTs. Based on the results of BlastN and the index of GenBank Accenssion No., the known gene expression profile of pig fat were constructed. It showed that the genes participating in metabolism held the highest proportion in the 7 sorts, and in some aspects showed the hearty metabolism activity of fat tissue. 257 total reads of the Major Histocompatibility Complex (MHC) genes in the pig fat tissue were found,including 181 singlet genes and 44 multicopy genes. They account for 44.9% of the cell and organism defense, and 5.4% of all known genes,from this we can see that the MHC has a fairly high expression degree. Comparing all ESTs related with MHC (257reads) with known pig BAC we found the partial sequences (approximately 200 bp) of the ESTs distributing to every exon of. We can predict that the ESTs in MHC contain approximately 200 bp highly consistent regions and every exon possesses one of these regions. Although these MHC sequences in different BAC have different protein domains,they are highly consistent and related with immune functions. When the MHC genes transfer to the next generation,they can duplicate repeatly and inherit stably.