The theologians of the Imamiyyah have relied on the "rule of grace" to prove some important theological issues. The question of the current research is, what developments has the rule of grace undergone in Imamiyyah theology, in three axes: definition, divisions and rulings? The research results are revealed in the form of four distinct periods. In the first period (before Sheikh Mofid), except for Abu Ishaq Ibrahim bin Nubakht, none of the theologians said anything about these three axes. In the second period (from Sheikh Mufid to Khwaja Nasir Tusi), the principle of favor with all the elements and topics that can be assumed for it (including the aforementioned three axes) appeared in the works of theologians - with differences in coverage, summaries and details. is The obvious point in the written works of the theologians of this period is the detailed expression, as well as the difference in the interpretations of the theologians in the explanation and exposition of the contents. The main difference of the third period (from Khwaja Nasir Tusi to the beginning of the 11th century) with the previous period is in the concise expression and unity of interpretations. In the fourth period (from the 11th century to the contemporary period), the contents are said in a concise and comprehensive manner, and the chapters and phrases are close to what "Allameh Hali" said; However, about the definition of grace, new points can be seen in some works.