With the interconnection of independent power systems, serious accidence rarely occurs due to single equipment outage. However when severe fault such as cascading failure occurs, blackout will cause major loss and should be warned in advance. Traditionally it’s very difficult to analyze cascading failures. Failures modes are too numerous to enumerate. Fault parameters may be continuous, such as fault position and duration, or discrete such as fault type and performance of protection systems. Performance of protection relays and emergency control measures should also be simulated in cascading failures analysis. A hybrid transient simulation method is applied in the paper, which combines the merits of deterministic and probabilistic methods. Original fault element is artificially designated. Fault parameter and performance of protection relays are sampled according to its probability distribution. Emergency control measures such as load curtailment and generator tripping, and protection systems such as over load tripping are simulated. By this way cascading failures with larger probability and serious effect can be automatically filtered out. Result and calculation speed in IEEE test system and an actual bulk system shows inspiring prospect in online application.