In this paper, an event network is presented for exploring open information, where linguistic units about an event are organized for analysing. The process is divided into three steps: document event detection, event network construction and event network analysis. First, by implementing event detection or tracking, documents are retrospectively (or on-line) organized into document events. Secondly, for each of the document event, linguistic units are extracted and combined into event networks. Thirdly, various analytic methods are proposed for event network analysis. In our application methodologies are presented for exploring open information.