This research is focusing on the epistemological pattern of Islamic education during the Abbasid dynasty, especially during the Caliph Harun ar-Rashid. This study is library research using a historical approach. The research findings indicate that the background influencing the development of educational epistemology during the Abbasid dynasty, especially during the Caliph Harun is the translation movement, the construction of Bait al-Hikmah, the high number of Islamic educational institutions such as kuttab / maktab, low education in the palace, procurement of bookstores, the existence of Knowledge Convention, optimizing the function of mosques, madrasas for the public, and providing houses for ulema. More, the existence of scientists around the Caliph Harun promoted the progress of science, civilization, and Islamic education. In addition, the advance of political stability and economic circumstances during the Caliph Harun had also made scientific activity, Islamic education, and knowledge development becomes maximum. Moreover, Islamic education epistemology during the Caliph Harun can be mapped into three major streams of the underlying theory of knowledge, first, rational knowledge; second, sensory knowledge; and third, knowledge of Kasyaf through revelation or intuition. Several forms of knowledge developed from the epistemological style of Islamic education include the science of interpretation, the science of hadith, the science of kalam, the science of language, and the science of Tasawuf. Epistemology of Islamic education spawned many methods for scientific study such as nadzr, tadabur, tafakur, bayyinah, burhan, mulahzah, tajrib, istiqra, qiyas, tamsil, ta'wil, dzati, HISSI, khayali, aqli, syibhi, and more.