Abstract: Copy number variation (CNV) is increasingly recognized as a source of inter-individual differences in genome sequence and has been proposed as a driving force for genome evolution and phenotypic variation. Many CNVs resulted in different levels of gene expression, which may account for a significant proportion of normal phenotypic variation and hu-man diseases. This review unveiled the research process and study strategy of CNVs. Subsequently, the potential mecha-nisms of CNV formation and its clinical implications were discussed. In addition, the first-generation copy number variation map of the human genome was introduced, which demonstrated that DNA copy number variation was associated with spe-cific chromosomal rearrangements and genomic disorders.