Apoptosis is a common mode of cell death occurring during development as well as in many pathological conditions, such as in tumor, aged and degenerative diseases. However, some experimental results recently demonstrate that free radicals involve in apoptosis. In apoptosis cells, the reactive oxygenspecies (ROS) production increases and the ability to metabolize ROS declines. The ROS in most disabled apoptosis cells is lower and the mortality of this kind of cells can be changed according to the amount of ROS in cells. Irradiation can result in apoptosis damaged by hydroxyl free radical，the apoptosis phenomena in some cells come from with drawing growth factor and medium may becaused by change of the free radical metabolic enzyme activity，such as peroxide hydrogen enzyme. The research summarized collectively suggest that free radical plays an important role in regulation of apoptosis.