Abstract: An essential feature of our time is the frequency of unconventional emergencies, whose striking features are extreme uncertainty and scenario dependence. The foundation to deal with them is to have a scientific understanding of situation. This thesis firstly discusses the original meaning of situation both in English and Chinese and sums up the basic definition of scenario concepts by analyzing and refining their general concepts at home and abroad. Then it summarizes extracts and classifies the representative definitions of domestic scenario concepts by associating the recognition of scenario concepts with unconventional emergencies. At last, this paper, based on the realistic demands of unconventional emergency management, divides situation into two parts, namely clustering type and decision-making type.