The invention discloses a public dose evaluation method based on a probability theory in radiation environment evaluation. The method comprises the following steps of analyzing and determining an irradiation path, the irradiation path comprising inhaled air internal irradiation, air immersion external irradiation, surface sediment external irradiation, internal irradiation of food-in animal and plant products and dose evaluation, and selecting a representative personal annual effective dose according to the result of the dose evaluation. According to the method, in the public dose estimation process, all the public within the illuminated range are considered, a reasonable personal annual effective dose is selected as a reference dose value, the value serves as an evaluation index in radiation environment evaluation, the conservative property of the evaluation index is further enhanced, and therefore the safety of the public and the environment is guaranteed.