Abstract: Deoxyribonuclease II (DNase II) is an important acid endonuclease in lysosomes, nuclei and various secretions in many animals. DNase II family member include DNase IIα，DNase IIβ，and L-DNase II. During apoptosis，DNase II can help apoptotic cells which were engulfed by phagocytic cells for digesting the DNA and contein correct development，viability and immune function. Review on the character and progression of DNase II lay a foundation of further study on its biological function and action mechanism in apoptosis.