In the last few decades, scholars of the Qur'an, with the structural interpretation approach, believe that this new method will significantly contribute to the understanding of the concepts of the Qur'an. This method primarily seeks to discover the primary and secondary aims of the surahs, and then to discover the relationship of the sentences and the verses to each other in drawing the secondary aims and to a higher space the overall purpose of the surahs. On the basis of this approach, the present article has examined the surah Sad by looking at numerous commentaries of Shiites and Sunnis, including al-Mizan. The results of the structural analysis of the surah Sad show that the focal point of this surah focuses on education and concentration of the Prophet (s) and consequently religious missionaries in their various duties in guiding and threatening the polytheists in the matter of mabda`, ma`ad and nubuwwat. And it is a prophecy, and these duties are mentioned in numerous cases. Praising some of the prophets and removing heavy accusations and preventing people from damaging their reputation has also been considered as well.