Abstract: Hazard, danger, harm, risk, etc. are the basic concepts of risk management in safety engineering, and the current understanding of these concepts in the academic and engineering communities is still under debate and development. Ordinary technicians in the relevant industries generally still have a vague understanding of the connotation and scope of various concepts, and it is difficult to clearly distinguish the relationship and differences between them. There are often improper use or even misuse in actual engineering. Based on review of relevant literature and research on the actual situation of the industry, this paper conducted an in-depth analysis on the definitions of 10 basic concepts such as hazard, danger and harm and further clarified the connotation and scope of each concept. The association model between the concepts of hazard, danger, harm and unsafe condition were established, and the logical relationship between the concepts was clarified. The general idea of the classification of hazard, danger, harm and hazardous elements were clarified, and the corresponding basic classification methods were put forward. This paper plays a guiding role in standardizing the use of basic concepts related to risk as well as specific tasks such as hazard identification.

Key words: risk, concept discrimination, association model, classification method