Abstract: In order to solve problem of insufficient knowledge organization, sharing and reuse of coal mine accident cases, the ontology was introduced into knowledge management of accident cases, and construction and reasoning technology of the ontology-based accident case knowledge base were studied. Based on analysis of the accident case knowledge, accident knowledge representation model and accident case body model were constructed. According to knowledge base model and construction method, the coal mine accident case ontology and rule base were constructed respectively, thus the knowledge base was constructed. Knowledge reasoning application based on the knowledge base of mine accident case was realized with gas accident as an example. The research results show that using the knowledge base of coal mine accident case can achieve the knowledge organization and knowledge automatic inference, and can greatly improve sharing and reuse of the mine accident case knowledge.