In Common Carp (Cyprinus carpio) IGF2b is an important member of IGF family, and the 5′ flanking region sequence contributes to its function largely. The 5′ flanking region sequence was cloned by genome walking method and the methylation of GC-rich region in the sequence was also analysed through sulfate-modified method. It was shown that IGF2b 5′ flanking region sequence was 695 bp in length. Multiple transcription factor binding sites and TATA box were found by TFSEARCH analysis. IGF2b 5′ flanking region sequence shared 87% identity with that of zebrafish as revealed by BLAST. Two individuals of Jian Carp(C.c.var.jian)had 3 methylated sites, while only one individual of Huanghe Carp (C.c.haematopterus) had similar modification among the 17 GC-rich regions examined. Thus, methylation modification level is low in this region, and this GC-rich sequence was stable in both Jian Carp and Huanghe Carp.