Load shedding can be driven by either faults（emergency load shedding） or trajectories（corrective load shedding）. To deal with many non-deterministic factors， it is important to coordinate them. According to a decoupling optimization and global coordination framework， power system stability and security are analyzed with FASTEST software package considering the non-deterministic factors， and then fault-driven load shedding and trajectory-driven load shedding are optimized respectively and interactively. During the course of optimizing one of them， the newest results of another are taken as constrained scenarios. Iteration is conducted until the total risk of all assumed faults is not reduced obviously. With consideration of the non-deterministic factors of the assumed faults， load model and load level， simulation studies undertaken on a power system show that the optimal coordinative load shedding scheme reduces the risk cost obviously with a premise of maintaining stability and security of the power system.