Strategic environmental assessment (SEA) has been implemented in many policies in the European Union since 2001. In Taiwan, SEA has been implemented for 28 cases since 2001, which includes various types of policies. National energy policy is the most challenging type. There are three most important steps in SEA process: alternative planning, scoping, and impact assessment. However, the current limitation of method application affects the effectiveness of SEA. In this case, life cycle assessment (LCA) is integrated with SEA for clarifying the role of LCA in whole SEA process. The method of combining LCA and SEA has been developed and is applied in a case of Taiwan's energy policy. Benefits from LCA in alternative planning, scoping, and impact assessment steps are explored. Finally, suggestions for enhancing LCA's application, for scoping operation, and for the improvement of SEA are proposed.