The Web Information Extraction and Knowledge Presentation System is proposed to extract information from data intensive web pages. It downloads dynamic web pages, based on a knowledge database, changes them to XML documents after preprocessing, finds repeated patterns from them, by using a PAT-array based pattern discovery algorithm, recognizes their data display structure models, automatically based on the repeated patterns and an ontology-based keyword library, and then extracts the data and stores them in the knowledge database with the object-relational mapping technology of XML. Through these steps, web data is extracted automatically, and the knowledge database is also expanded automatically. Experiments on the traffic information auto-extraction and mixed traffic travel schemes auto-creation system showed that the system has high precision and is adaptive to web pages in different domains with different structures.