In narrative texts, different kinds of evidence are used for more acceptability. This topic is defined as ‘, evidentiality’,in linguistics. F. R. Palmer is one of the semanticists who divides this category into two types: sensory and reported, and also states several types for each one of them. In this research, all types of evidential markers have been studied based on the following features: visual (direct and indirect), auditory, sense of smell, the sixth sense, similarity, types of report, experience and cognition, rational signification, prediction (astronomy and dream interpretation), Yezidis Xvarenah, swearing an oath, and witnessing. The findings indicated that the markers of guess, though including uncertainty and skepticism, occur in the entirely factual status of preposition. In the discourse of characters (princes, heroes, mowbeds, astronomers, etc. ), because of the high rationality of sender, the guesses come true, and the contrary conditions never do happen. Among the evidential features, inference from signs, regarding its participation in all the other types of evidentiality, is considerable. Verbs such as "didan", "š, enidan", "buyidan", "dā, nestan", "ā, gā, h š, odan", and the metaphors like "be del ā, madan", and the other words including "gomā, nam", "guyi", and "bar ā, nam" are instances of evidential markers used in Shahnameh.