Cascading failure is one of the key factors resulted in large-scope blackouts， and can be properly characterized by the fault chain. The model established for cascading failure of a grid based on the fault chain is the basis of prediction and preventive control for cascading failure， and has important significance to prevent the occurrence of blackouts. Based on the major factors of the process of cascading failure， by using the existing analysis tools（such as PSASP etc）， the fault chains model for cascading failure of grid is established. According to the relationship between the fault chains and cascading failure， failure scenario is placed restrictions on power supply paths， thus the computational load is effectively reduced. Taking advantage of the fault chains model of cascading failure， cascading failure is monitored and preventively controlled by using the relevant methods of safety science. The practical application of Jiangxi Power Grid indicates that this method is very effective for analysis on service interruption to regional grid or power failure of a power plant， and it has been applied to the grid planning.