Abstract: Mitochondria, which can produce and supply energy for mammals, are involved in many cellular events of growth,development,aging,apoptosis as well as diseases. Nuclear transfer could result in mitochondria heteroplasmy in cloned embryos and offspring, affecting the phenotypes of the individuals and even causing mitochondrial diseases. This text has expounded the biological functions and the hereditary characteristics of the mitochondria in mammals, and analyzed the change of donor and recipient mitochondria in embryos and offspring derived from intraspecific and interspecific embryonic or somatic nuclear transfer as well as several factors which might influence mitochondrial heteroplasmy in the process of nuclear transfer. The mitochondrial diseases it may cause and their solutions are also briefly presented.