The intrinsic and extrinsic development of NATO permeated its history.The former is the development of the political-military structure of NATO;the latter is its enlargement and special behaviors in the international affairs.In the Cold War Era,the ideology played the most important role in the establishment of NATO's system and the enlargement of NATO.In the Post-Cold War period,hegemonism,unilateralism and ideology of the Cold War are contributing a lot to the strategy,transformation and enlargement of NATO.