Abstract: Imam Shafi'i is one of the Imam of the fiqh schools of the four schools of fiqh. Imam Syâfi'î is a teacher of Imam Ahmad and he is also a student of Imam Mâlik and has also studied with a student of Imam Abû Hanîfah namely Imam Muhammad Ibn al-Hasan al-Syaibanî. Therefore, Imam Syâfi'î fiqh was formed from across intellectuals with a combination and meeting of knowledge of fiqh ahl al-hadîts (Imam Mâlik) and fiqh ahl al-ra'y (Imam Abû Hanîfah). This paper aims to examine Imam Syâfi'î as a mujtahid and Imam of the Fiqh School in historical, juridical and sociological studies. Imam Syâfi'î succeeded in formulating the legal thought of ahl al-hadîts, the version of Imam Mâlik with the thought of the law of ahl al-ra'y, the version of Imam Abû Hanîfah. The epistemology of the ushul fiqh of Imam Shafi'î in istinbath al-Ahkam, namely al-Quran, as-Sunnah, ijma ', qaul shahabi, and qiyas. The uniqueness of Imam Syâfi'î fiqh with the existence of qaul qadim and qaul jadid is also influenced by the social setting in which the fatwa was formulated.   Keywords: imam shafi'i; mujtahid; imam of fiqh schools; islamic legal theory; islamic jurisprudence