The economic development, environmental sustainability and energy security stay on the top of government agenda, which guarantee the citizen¡¦s standards of living . EU's indigenous energy production is depleting, and each states has different priorities. The European Union push new European energy policies improving security of energy supply ,which are aiming at reducing the risks being dependent on external supply. Those new european energy policies transform Europe into a highly energy efficiency and low CO2 economy,creating an internal energy market and diversifying energy supplies. The EU¡¦s internal policies include enhancing powers and independence of regulatory authorities at Community level, improving the integrated and flexible energy networks,establishing adequate minimum security of gas supply standards and emergency measures and executing the Action Plan for energy efficiency. The EU¡¦s external policies include enhancing energy partnership and continuing energy dialogue with Russia, Central Asia and Mediterranean area, improving investment and growth, developing common trade,transit and environment rules, building the energy supply chain and diversifying energy supplies. In this thesis the security of EU¡¦s energy supply will be examined by the perspective of neo-functionalism.