ʿIlm Al Rijāl (A discipline of Islamic religious studies within hadith terminology in which the narrators of hadith are evaluated) is a basic and value able discipline in the field of Hadith &Ulūm Al Hadith. All Muhaddithīn are strongly agreed on this fact that non-existence of this discipline of study may permit to any person to say anything at any time in the matter of Hadith. So, ʿIlm Al Rijāl has secured the sayings of Prophet Muhammad PBUH and his companions RA as well as it also provided us biographies of half million Narrators of Hadith from the early period of Islam. ImāmBukhārī is a famous and important figure among those Muhaddithīn who provided their services in this discipline. As such ImāmBukhārī compiled many books on Aqā’id , Tafsīr , Hadith and ethics etc, he also wrote almost ten books(Al Tārīkh Al Kabīr , Al Tārīkh Al Ausat, Al Tārīkh Al Saghīr, Al Kunā, Al Duʿāfā Al Saghīr, Asāmā Al ṣahāba, Kitāb Al Waḥdān, Kitāb Al ʿilal, Al Duʿāfā Al Kabīr, and Al Mashikha) on ʿIlm Al Rijāl. In this article I’ll try to find out and explain the methodology of imam bukhari in his basic and majestic book “Al Tārīkh Al Kabīr” with narration of its value ability, popularity and necessary introduction.