Inhibitor of apoptosis proteins (IAPs) constitute a family of proteins that contain one to three baculovirus IAP repeats(BIR). This IAP family ensure cell viability through binding to caspases with the BIR domain and regulating their activity in a ubiquitin-dependent manner. While IAPs are regulated by their antagonists. To investigate the regulation pathway of IAP, we have cloned and sequenced the Cqiap gene of Culex quinquefasciatus from China by RT -PCR. It's 1230bp in length. The putative protein of Cqiap contains two BIR domains and one RING finger domain. Cqiap is highly identity with iap of the published Culex quinquefasciatus (GENE ID: 6032833, 99.6%). Multiple sequence alignment and phylogenetic tree analysis show that animal IAPs were classified into two major groups. As to the species we list in this paper,one group is from invertebrate IAPs with two BIR domains, the other group contains invertebrate and vertebrate IAPs with three BIR domains. The reported IAP of Culex quinquefasciatus from China falls into the group of IAPs with 2 BIR domains.