Distance learning can be facilitated through e-learning, and students can enhance their understanding of course materials through the use of an intelligent querying system that enables self-learning. In this paper, an ontology-based method for organizing the knowledge of mathematics in high-school is presented. Ontology Rela-Ops model, which is a knowledge model for representing the knowledge of relations and operators, is combined with the knowledge component of functions. Based on the combining model, a structure of knowledge graph is proposed to represent relations of intellectual contents. An intelligent querying system is designed for the domain of high-school mathematics using these structures. This searching system can query contents of the course and extracts other knowledge related to querying results. The experimental results show that the proposed method is useful and effective to apply in the practice.