Bystander effects are the subject of intense investigation in radio-biology. Described in the biological effects in non-targeted cells observed responses in cells targeted by ionizing radiation. The purpose of this review was to consider bystander effect in areas of major importance or mechanism produced and pass way. These include consideration of composition material of the damage factor produced and even the relevant of radiation dosage that supports it, is also discussed. The research of Bystander effect can reveal the new conception of the radio-biological effect, and so as to have further consideration and application in assessing radiation damage radiotherapy effect.