In this paper,we study the natural background of disaster occurrences,especially the impacts of geological tectonic,monsoon climate and geomorphological factors on the disasters. The regionalization of natural environment producing disasters is laid down. The resultshows that there are two main areas producing disasters,which are northern plain and southern hills.Ten subareas prone to disasters are divided based on the geomorphological types.We also analyse the background of socioeconomy,area capacity of bearing disasters and impacts of human activities on the disasters. On the basis of the interactions among all the components in the earth system and the impacts of external forcing factors on the disasters,theoccurrence and development of disasters are discused.