Abstract: Security vulnerability assessment methodology is used to identify and analyze the threat and the vulnerability of facilities which operators concern. The result of the security vulnerability is a relative vulnerability risk level. Based on the basic strategy in prevention, inspection, mitigation, response, the security goals and a rational, economic and feasible prevention system specific to the vandalism and terrorist attack are established, and appropriate risk management decisions are made. Security vulnerability assessment process includes five steps: identification characteristics of assets and assessment, threat assessment, vulnerability analysis, risk assessment and measures analysis. The purpose of security vulnerability assessment is to allocate the limited resources rationally, and achieve maximum safety and security under the minimum investment. An instance about the key functions and key assets for some pipeline is given. The appropriate circumstances, the type of security incident, threat classification, consequences, existing measures and vulnerability are analyzed, and corresponding measures are suggested. The method is adopted to well evaluate the risks of terrorist activities for oil and gas pipelines and is helpful for establishing an appropriate prevention system.