Abstract: Preimplantation genetic diagnosis （PGD）is a method to analyze embryo hereditarysubstance before implantation，and to identify which embryo is normal and suitable to transfer. PGD is one ofthe essential parts of assisted reproductive technology （ART）. With the development of the detectingtechniques，more technologies were applied in PGD. Single nucleotide polymorphism array（SNP array）isa newtechnology of PGD, with many advantages of fast diagnosis，screening for 24 chromosomes in one time，highresolution，detection of uniparental disomy. The origin of implanted embryo or the origin of extra chromosomefrom abnormal embryos can be found by SNP array. In addition, SNP array is widely used in other fields ofassisted reproduction.

Key words: Preimplantation diagnosis, Genetics, Polymorphism, single nucleotide, Embryo transfer, Microarray analysis