Abstract: In order to study the unconventional emergency evolution mechanism, improve the emergency prevention, control and rescue capability, based on the original four evolutionary patterns, this paper adopts the cusp catastrophe model of catastrophe theory to analyze unconventional emergency events. With the case study of the mass events result from the dangerous chemical accidents in Dalian, it expands the evolutionary patterns of unconventional emergency events and improves the unconventional emergencies evolutionary mechanism. It provides technical supports for the emergency warning system.