线粒体DNA拷贝数是线粒体DNA在线粒体基因组中的个数，目前存在几种线粒体DNA拷贝数调控模式假说。线粒体DNA拷贝数受线粒体转录因子A、同源重组修复蛋白Rad51、DNA聚合酶γ等的调控。氧化应激对线粒体DNA拷贝数的影响与其对线粒体DNA的损伤程度有关，呈双向调节作用。近年来研究发现，线粒体DNA拷贝数变化与骨质疏松、糖尿病、心血管疾病、肿瘤等多种疾病的发生、发展有一定的相关性，且在不同疾病或疾病发展的不同阶段变化不同。“,”Mitochondrial DNA copy number is the number of mitochondrial DNA in the mitochondrial genome which has several hypotheses about the control patterns of it. Mitochondrial DNA copy number is reg-ulated by mitochondrial transcription factor A,homologous recombination repair protein Rad51 and the specif-ic DNA polymerase gamma etc. The impact on DNA copy number caused by oxidative stress is both-way regu-lated,which is linked with the degree of oxidative injury. In other words,mitochondrial DNA copy number in-creases with mild oxidative stress,while it decreases in severe circumstances. In recent researches,it has been found that the change of mitochondrial DNA copy number has a certain relevance with osteoporosis,diabetes, cardiovascular disease and cancer etc. Moreover,mitochondrial DNA copy number varies in different diseases and distinct phases in development of certain diseases.