To fully research random event on financial markets and then accurately analyze the following event, namely expected event, a double regression discontinuity model is proposed from the whole sample perspective. It is pointed out that this new model and its conclusions are in the unified modeling framework. Then, taking the“Changsheng vaccine” and “Changsheng delisting” event as examples,twice regression discontinuity calculations and the double regression discontinuity calculations are performed. The results show the superiority of the proposed model in the study of expected events from the aspects of fitting effect, parameter trend, robustness, and practical connotation. It also shows that China’s pharmaceutical market is mature, suggesting more attentions from rational investors. These conclusions provides references for relevant investors and regulators to deal with random events on financial markets in the future.