Abstract: Poly ADP-ribose ploymerase (PARP) is a kind of ploymerase which widely exists in cells, has the function of protein modification and nucleotide polymerazition, and participates in the repair processes after DNA has been damaged. It has been proved that PARP has lots of physiological and biochemistry functions and correlates with cell death. Many kinds of damage factors such as radiation may influence the activity of PARP.