Familiarity and interest in the principles of civilization, culture, science and knowledge of Western countries and the application of their experiences and knowledge in Iran by sending students to those countries including the United States, was cone of the ideas of many Iranian statesmen and reformers.   The present article focuses on these questions: why Iranian students were interested in going to the United States? What role did Iranian diplomats in the United States play in the entry of Iranian students into this country? And in what field did the students study? The paper, based on unpublished documents uses the descriptive-analytical method. The findings of the study indicate that the weakness of the Iranian education system and the ineffectiveness of sending students to Europe led Iranian political representatives in the United States to pursue the policy of studying Iranian students in the United States. Ali Qoli Khan Nabil al-Dawla and Hossein Alaei were among the diplomats who, by sending numerous reports to the government about US development in the field of science and education, succeeded in allowing Iranian students (even female students) to enter the United States and study in fields such as military technology, agriculture, medicine and engineering. In the last years of Qajar rule, scientific and educational relations between Iran and the United States improved, therefore, a significant number of Iranian students who were sent to the United States after graduation returned to Iran to serve the country.