DNAs with catalytic potential isolated from a ssDNA pool with random-sequence in vitro selection, were called deoxyribozymes or DNAzyme.Deoxyribozymes that exhibit RNA transesterification ,DNA transesterification,porphyrin metalation and peroxidase activities,DNA kinase activity and DNA ligase activity have recently been reported. Deoxyribozyme 10～23 might act as a sequence-specific RNA endoribonuclease in vitro,and could be used to inactivate target cellular RNA in vivo.