At present the insufficient formal business knowledge participation in the process of On-Line Analytical Processing (OLAP) results in restriction and limitation to in-depth analysis. To overcome the limitations, a new approach for building an OLAP system was proposed based on domain ontology. Firstly, by analyzing the limitations of the existing ontology construction methods and using the similarity evaluation algorithm based on multiple features and weighted pattern of entity classes, a semi-automatic domain ontology construction method in which global top-level domain ontology was designed by experts after local ontologies were generated from databases was put forward to implement formalized description of mine-production domain knowledge. And then the key indicators of mine-production capacity were chosen as measurements and Multi-Dimensional Ontology (MDO) with business semantic concepts was built. Finally, the method was tested by a practical project of metal mine decision making system. The experimental results show that the proposed method can dynamically integrate heterogeneous information resource of mine production process and facilitate the unambiguous interpretation of query results, and discover association rules and implicit knowledge through the advantages of formalization expression and reasoning of domain ontology. Meanwhile, by high frequency and general concept views, it avoids query duplication and improves the performance of traditional OLAP systems.