Order, as the basic rational concept to understand the meanings and to reason injunctions, has been the concern of the intellectuals of the exegesis scope and Islamic jurisprudency since the remote past. to consider the quality of the implementation of this intellectual instrument and its transformation trend as a term in verbal meaning to its rational rule in the Shi’ite juris merits deliberation.The Shi’ite Jurists, from the Sheikh Sadooq down to the 8th century, did not consider a meaning for Order (Siaq) more than the Order of Guidance as well as the verbal meaning, but in the following centuries, some of the jurists accepted Order as an important rational instrument in the process of Ijtehad, especially during the contemporary era, the unity of Order has been considered as a bas ic characteristic of Order by jurists.The Shi’ite jurists, unlike the application of Order in jurisprudence, have not defined it, so the present paper is concerned with the investigation of the functions of the jurists, which is important for the understanding of the meaning and the purpose of implementations.