From the very last days of the reign of Muhammad Shah Qajar (r. 18341848-) to 18921309/, Mirza Moheb’Ali Khan Nazem-ol Molk, as one of the Foreign ministry officials, takes over the main responsibilities in Iran and Ottoman demarcation for more than fifty years. He began his work as an assistant for Mirza Ja'far Khan Moshirol-Doleh who was the head of Iran and Ottoman border commission. After the death of the latter, he succeeded the position and maintained the office for some decades. Despite decades of practical efforts and writing treatises and taking part in various border commissions to defend the territorial integrity of Iran, He is still, unfortunately, one of the unknown statesmen in the Qajar era. Studies on the lives of influential figures in the contemporary history of Iran, unfortunately, focus on the lives of a few distinguished figures. This study, through use of historical approach and descriptive-analytical method and use of archival documents and manuscripts, particularly those remaining from Moheb’Ali Khan, answers the following questions: Who is Mirza Moheb’Ali Khan? What is his role and function during the five decades of his actively involved in the field of foreign relations? The results of this study shows: He was raised by the tradition of great statesman like Mirza Ja'far Khan Moshir-olDoleh. He was successful for decades in Iran's foreign relations, especially with the Ottoman and British political negotiations for the delimitation of boundaries in the West and North East of the country, with competence all defend the territorial integrity of Iran. Documents left behind him, confirms this issue properly.