The invention relates to a method for performing low-dosage radiant biology early warning by utilizing luminous bacteria. According to the method, a dosage-effect relationship between a radiant dosage acceptable by the bacteria and a luminous intensity can be established by utilizing a sensitivity of the luminous bacteria to the low-dosage radiation, and the luminous intensity of the bacteria has positive correlation with the activity of luminous elements such as fluorescein, luciferase and ATP in the bacterial cells. Therefore, through calculation of a luminous intensity suppression ratio of the luminous bacteria, the comprehensive toxicity of the low-dosage radiation for the luminous bacteria can be estimated, and a biology early warning method is established. The method for performing low-dosage radiant biology early warning by utilizing the luminous bacteria has multiple advantages of being convenient, simple and fast to operate, low in cost, high in sensitivity, good in accuracy, low in environment risk and the like.