Discuss and develop the software agent for intelligent business terminal system according to the requirements of the intelligent business terminal capability. This paper discusses the architecture of the intelligent business terminal system and the function modules of the intelligent terminal agent. It also discuss two-leveled ontology architecture to provide intelligent agent knowledge support better. This paper proposes an ontology knowledge representation language HDF (Helper Definition Format) based on XML/XMLS specification to describe plenty of the agent contents based on ontology. It also introduces the HDF specification, using methods and processing mechanism, and how the intelligent business agent works based on HDF for business terminal.