Abstract：The natural disaster chain in the form of mathematical language on the basis of the system analysis methods is defined，and its property based on the disaster chain mode is studied. This paper studies the chain-cutting disaster mitigation from the point of its inner state and the outside environments，and points out that the outside environment influence is gestation sources of disaster and disaster chain，and reveals that disaster chain exists because of the interaction of disasters. An example in view of land desertification chain is presented. The land desertification chain results from human unreasonable activities and from the deterioration of ecological environment are drawn，and chain-cutting disaster mitigation of land desertification chain by the disaster chain mode is analyzed.
