It is important to provide adaptive data processing in wireless sensor networks in order to deal with various applications. In this paper,we propose a WIreless Sensor Networks Ontology (WISNO) for flexible modeling of sensor data. WISNO contains two-tier ontologies, a front-end for coarsegrained analysis and a back-end for high-level fine-grained data processing. We also describes the WISNO reasoning rules that adopts description logic and SWRL for managing data automatically. Categories and Subject Descriptors C.2.3 [Computer-Communication Networks]: Network Operations—Network management General Terms Management, Performance Keywords Wireless Sensor Networks, Ontology, SWRL, description logic