The principles of jurisprudence as a methodology of jurisprudence that discusses the rules and principles that satisfy the need of the jurist in deriving rulings from the authoritative sources, such as the Quran, Sunnah and intellect ('aql). The main question that this article seeks to answer and explore is, what was the theory of understanding the text according Shia scholars of ʿIlm al-Uṣūl when faced with the sources, such as the Qur'an and the Sunnah? This theory, which has been less explicitly addressed and has been mainly dealt based on the scholars' orientation, is the determining factor of the rules that the principles of jurisprudence must deal with, and it is the factor of discerning the rules that are not approved by the scholars of Uṣūl. The central idea of ​​this theory is to adhere to the principality of the apparent meaning, which, with other aspects that are the crystallization of this principle and which complement it, forms the theory of understanding the text of the Uṣūlīs. This article, by focusing on epistemological and non-epistemological factors affecting the knowledge of the jurist, and considering the requirements of two other components, i.e. the jurist as the author and the text as the mediator between the legislator and the jurist, attempts to take a positive step towards designing the aforementioned theory.