The purpose of this study is to explain the position of reason in axiology (fields of ethics and aesthetics) from the perspective of Nahj al-Balaghah. This research uses a descriptive-analytic methodology with inductive approach. The research findings indicate a two-way relationship between reason and axiology from the perspective of Nahj al-Balaghah. On the one hand, reason is the most important tool in discovering moral values, and on the other hand, moral virtues cause the correct functioning of reason. In addition, the beauties of the created world are worthy of reflection, and contemplation of them causes the penetration of the existing harmony into the mind and the flourishing of understanding. Nonetheless, due to the limitations and errors of reason, the use of experience and narration as complementary tools in axiology is recommended, and the divine revelation has the final say. On this basis, it can be stated that the position of reason in axiology is a moderate position. However, according to God’s expectation of man to the extent of the intellect bestowed on him, it is necessary for the researcher to recognize and judge it in valid axiology and to have them crystalized.