The confrontation between Iran and the United States after the Islamic Revolution had many ups and downs, which intensified in the fifth decade of the revolution with getting into power of the Trump administration. In this regard, the US Congress, as one of the most important pillars of the power structure through legislation and oversight, has played an undeniable role in US foreign policy towards Iran over the past forty years. The purpose of this article is to review the actions of the 116th US Congress towards Iran and its role in US foreign policy. Studies show that the 116th Congress, under the widespread influence of the Zionist lobby, has organized numerous legislative and monitoring activities against the Islamic Republic of Iran and the control of its elements of power, including nuclear and missile capabilities and regional power. However, in the second year of its actions, with the escalation of tensions in the region, especially after the assassination of general Soleimani and the Iranian missile attack on the Ain al-Assad base, Congress focused on controlling the Trump administration's belligerent policies to prevent a military strike against the Islamic Republic. The most significant actions of the One Hundred and sixeenth Congress, including a joint bill and resolution, have been taken in this regard. It seems that despite the Trump administration's countermeasures to neutralize the resolution passed by Congress, the activities of the 116th Congress have been one of the most effective factors in preventing a full-scale war against Iran.