Abstract：Environmental risk regionalization is an important method for regional environmental risk management. Based on the theory of environmental risk system, the traditional regionalization method which combining the top-down with bottom-up was adopted to analyze the Shanghai environmental accidents risk. The zoning regions were formed through the space variation of Shanghai history environmental accidents. Furthermore, the indicator system of environmental risk regionalization was established to realize the risk on the basis of index quantification, and the K-means algorithm was used to conduct the similarity combination of smallest regionalization units. After adjusting the cluster fragments, the environmental risk sub-regions were obtained. Taking into account the top-down and bottom-up regionalization results, the integrated zoning of Shanghai environmental risk was achieved. Shanghai environmental accident risk regionalization comprised two big regions, five sub-regions and twenty one districts. The corresponding suggestion to different type of environmental risk regions were also put forward in the paper to guide Shanghai environmental risk management and accident emergency response.
