With the formation of interconnected power grid of China as well as the requirement of integration of power generation scheduling among multi-level dispatching centers，it is increasingly imperative to improve the speed of the 96-period cases' security analysis for generation scheduling.Based on an analysis of the security characteristics，four fast computation methods are presented in terms of algorithm optimization，parallel computation，data reuse and other aspects，namely，the fast contingencies filtering，multi-process parallel computation for multi-period cases，data reuse based on topological characteristics and multi-thread parallel computation for a multi-contingency case.Detailed test examples of real power grids show that the methods proposed are effective in significantly improving the speed of96-period cases' security analysis.