miR-34a resides in the region of chromosome 1p36.23, which regulate a plethora of target genes. Ectopic miR-34a expression can induce apoptosis, cell cycle arrest and differentiation, meanwhile reduce migration of tumour cell which known as tumour inhibiting factor. p53 was shown a capability of activating miR-34a expression and miR-34a was also shown a feedback regulation to p53 gene in reverse. Ectopic expression of miR-34a induced by ionizing radiation plays an important role in DNA damage repair, apoptosis, cell cycle and cellular radiation sensitivity. This article reviews the progress in produce of miR-34a during ionizing radiation and its participation in biological response and relative mechanism in control.Cited