The country that is on the exact opposite side of the Earth from China is Argentina. If you were to draw a line straight through the Earth from China, it would pass through the Earth's core and come out on the other side in Argentina. This is often referred to as the antipodal point or the antipode of a location. Keep in mind that the antipodal point is not an exact spot but rather an approximate location due to the Earth's slightly irregular shape and variations in its density.