With the popularity of the Internet,Internet pornography is flooding the entire network,which degrades social conduct,and especially has done great harm to the mental health of minors.The paper analyzes the principle and key technology of network anti-pornography system inside Windows Vista operating system.After discussing a new network filter system-WFP,the paper designs and implements a network anti-pornography real-time filter driver based on WFP and Regular Expression inside Windows Vista operating system.We put forward a kind of new filter technique which adopts a special second-class form structure.Practice shows that the system is a good practical design.