Abstract: The appearance of semantic networks brings a new challenge for the use and management of personal privacy.An appropriate ontology needs to be developed to solve inconsistent question of the privacy expression and the use description in the electronic commerce domain.This paper uses the ontological method to discuss privacy ontology building,introducing specifically the ontology's construction principle and methods,and introduce the privacy ontology architecture using OWL.At the same time,this paper gives a demonstration of the privacy ontology in a semantic Web application.The building of privacy ontology lets privacy knowledge to be shared,reused and managed.It will establish a foundation for the further research into semantic web's privacy protection technology.