Abstract: It is important issue for assisted reproductive techniques（ART） to improve the pregnancy rate and security. As the most abundant organelles in oocytes，mitochondria not only take part in the energy supply for oocyte maturation, fertilization，transcription and translation during embryonic development，but also play roles in some key procedures such as the oocyte activation，calcium oscillation，and apoptosis. More importantly，all mitochondria in embryo were originated from oocyte，not the sperm. It has been demonstrated that mitochondria dysfunction is closely related to oocyte aging，low fertilization rate，poor embryo quality，and developmental arrest of embryo，etc. In this paper，the roles of mitochondrial function in oocyte maturation，fertilization and embryo development, as well as how to protect oocyte mitochondria and how to improve the function of oocyte mitochondria during ART, were reviewed.

Key words: Assisted reproductive techniques, Ovum, Oocytes, Mitochondria