GPR40 is one of the G protein-coupled receptors, which has 7 transmembrance spanning helical bundles. GPR40 distributes in pancreas and central nervous system. It can be bound by medium and long chain fatty acid and activate the intracellular signal pathways, which in turn regulates the function of cells. In b-cell, intracellular calcium concentration elevates when GPR40 is binding to fatty acid, thereby promoting the release of insulin. According to the theory, new drugs, the agonist of GPR40, have been used for prepreventing and treating the diabete as. In the nervous system, GPR40 is involved in neurogenesis, but the mechanism how GPR40 works is unclear until now. In this review, the research progress of GPR40 was reviewed, especially about the structure and characteristics of GPR40 gene, ligands and function. We focused on the problems encountered in the current research and the hot points in the future.