To solve the current problem of dynamic threat assessment of radiation sources,a threat assessment algorithm based on attribute reduction-improved TOPSIS is proposed,and a dynamic threat assessment model is constructed by introducing the combination weighting method and the time weight calculation method based on time degree.Attribute reduction is carried out according to the dominant relationship of the information system,and then the combination weighting method is used to calculate the attribute weight.The TOPSIS method is improved based on the measurements of the Euclidean distance,gray correlation degree and generalized Mahalanobis distance,and the weighted comprehensive proximity degree is calculated.In combination with the time weight,the final threat ranking is realized.The simulation results have verified the rationality of the proposed algorithm.Compared with the traditional evaluation method,the proposed algorithm has higher reliability and the parameters can be adjusted according to the preferences of decision makers with strong flexibility.