According to disaster system theory and the natural disaster database of China, this paper builds the urban vulnerability index on the basis of the integrated urbanization level index (CL) of hazard-affected bodies; and considering the structural damage and the influence on traffic of different natural disasters, this paper chooses five major disaster types (including flood, earthquake, debris flow-rock slide, typhoon and dust storm) to build and compute the integrated intensity index of major natural hazards (QC). Then through qualitative analysis and semi-quantitative calculation, the integrated urban risk of major natural disasters in china is divided into five grades, namely very high, high, medium, low and very low grades, and the corresponding assessment map is worked out. At last, some further discussion is done about the integrated risk assessment of natural disaster chains.