On 1 January 1995 a new international economic organization came into being. The WTO is either a modest enhancement of the GATT or a watershed moment for the institutions of world economic relations reflected in the Bretton Woods system. Indeed, the WTO Agreement, including all its elaborate Annexes, is probably fully understood by no nation that has accepted it, including some of the richest and most powerful trading nations that are members. And for a long time we just focus on the agreements on the global levels but how about the actually domestic application of treaties? This article will try to analysis the basic domestic application of WTO treaties and take American as a typical example. Then try to get tentative conclusion about the elements that effect the domestic application of WTO agreements.