The course of reinforced concrete structure design principles has the characteristics of multiple concepts, contents, symbols and formulas. How to effectively study, teach and expand this course has become the key for the teaching reform of reinforced concrete structure design principles. The philosophical concept of ontology and the modeling steps of ontology model are introduced, the main teaching contents of the course are integrated with ontology, and the refined ontology model for the main teaching contents of the course is constructed. Considering that Bayesian thinking can update and improve people’s understanding of the objective world, based on the ontology models of the main teaching content for the course, with the relevant information of the service reinforced concrete components, Bayesian method is used to expand the ontology models, which can deepen students’ mastery and understanding for the course contents, improve students’ professional cognitive ability and teachers’ teaching quality, and provide a new teaching method for related courses of civil engineering.