Abstract：As external shocks, emergencies bring more uncertainties to systematic risks. Unexpectedness and asset price bubbles can interpret the characteristics of systematic risk in the new situation. Focusing on the process of risk accumulation and release, this paper interprets the generation logic and evolution process of systematic risk from the theoretical perspective of regime switching under emergencies, and empirically analyzes typical facts of the capital market and the dynamic movement path of systematic risk in the field of regime switching. The study finds that systematic risk has nonlinear regime features and the regime transition of risks has ratchet effect; China's capital market stably stays within the risk accumulation regime, it is less likely to jump into the high risk regime and fall back to the low risk regime. However, emergencies can break asset price bubble that has been accumulating for a long time, and the quick break of bubble breakthrough threshold is very likely to cause systematic risks. Therefore, it is extremely urgent for China's regulatory authorities to bring emergencies into the risk normalization governance, prevent sudden regime transition caused by unexpected shocks and promptly defuse the rapid release of systematic risk caused by a series of emergencies.

Keyword：Systematic Risk; Emergencies; Regime Switching; Release and Defuse; Asset Price Bubble