The EU now faces many challenges of energy security, such as energy shortages, international market competition, climate change and dependence on import of energy. Any single member state will not be able to solve these problems independently. Although the member states have different interests in energy supply, leading to lacking political will to take the same position, it is necessary that the EU "speaks with one voice" in foreign energy policy. At present while the EU establishes or deepens the strategic partnership with the third countries, energy security plays a very important role. This paper discusses the EUs energy security, analyzes the contents of the strategic partnership, and explores how the EU uses the bilateral cooperation with his strategic partners to ensure the energy security.