The principal objective of process hazard analysis is to identify hazard scenarios.Both the course of team brainstorming hazard evaluation and its result information can be expressed as hazard scenarios. Ontology of hazard scenarios is accurate expression of standardized process hazard analysis information.An ontology is an explicit specification of a conceptualization.According to design criteria for ontologies，a standardized process hazard analysis information called scenario object model (SOM)was proposed.SOM was used to represent contents and structures of hazard evaluation information.Computer automatic reasoning and semi-quantitative algorithms could be implemented on SOM.Computer-aided automatic hazard evaluation and transfer，auditing and sharing of safety information were realized effectively by using ontology SOM.