Primary radiation effect on molecular level, energy deposition of radiation on micro-tissues, the cellular damage induced by micro-dose effect of secondary electrons and the cell survival contributed by gene micro-dose effect were introduced in this paper. In order to quantitatively describe various micro radiation effects, to understand more accurately evaluated events induced by low dose radiation, as well as to especially estimate the healthy risk exposed to low dose radiation, the items of micro-dose and micro-dose events were introduced.Cited