The emergence of Iran’s nuclear issue has provided new contents for the strategic battle between the United States and Russia. The United States and Russia had fierce competition and limited cooperation over Iran’s nuclear issue. The performance and the role of the United States and Russia on Iran’s nuclear issue ultimately depend on the strategic relationship among the United States, Russia and Iraq. US-Iraq hostility and strategic conflict are basic dominant elements in this strategic triangle. Because the United States needs Russia's support on the nuclear issue and Iran needs Russia as a barrier to guard against pressure from the U.S., thus Russia is profit-making at both sides in this strategic triangle.