Embryonic stem cell is promising for regenerative medicine. However, its application is hampered by the utilization of eggs in most established methods. Recently, a new pluripotent stem cell establishing method was reported that, mouse and human differentiated cells could be induced reprogrammed into a pluripotent state by expressing exogenetic stem factors such as Oct4, Sox2, et al, through retroviral transduction. This approach avoiding egg use is a great breakthrough not only in stem cell technology but also present theory hypothesis of reprogramming. Here these works were reviewed in this article. Both the mechanism of induced reprogramming and the prospects of induced pluripotent stem cells were discussed.