It had been a long time to study the effect of mitochondria in the regulation of cytosolic calcium signal. Recently, following the development of new method and technology, it is found that mitochondria plays an important role in calcium signaling. Mitochondria can sense the existence of surrounding calcium microdomains and uptake Ca²⁺. It can also release Ca²⁺ through 2Na⁺/Ca²⁺ exchanger and mitochondrial permeablize transition pore. Therefore, the time-spatio characteristic of cytosolic calcium signal can be regulated and related cellular function can be affected by mitochondria. However, due to the limitation of technique used now, confused and contradictory results are often obtained and further exploration is needed.