In the jurisprudence of the subject, which refers to reflection on the subject and the effort to find its main goal, it is of great importance in ijtihad. In the field of ijtihad, it may seem at first glance that the jurisprudence of the subject is not of much importance in inference; however, it must be said that the inference operation is almost meaningless without paying attention to the jurisprudence of the subject and should be considered a fruitless effort. Among the advantages of addressing the jurisprudence of the subject are facilitating ijtihad, increasing the quality of ijtihad, and reducing errors in ijtihad. Accordingly, the present study aims to explain and analyze the jurisprudence of the subject and its mechanisms in the jurisprudential method of Imam Khomeini. The previous study, using a descriptive and analytical method, has determined that desirable inference requires subject matter jurisprudence, and according to the findings of this study, subject matter jurisprudence must have four mechanisms such as perspectives (idea, thought, theory), information, techniques, and organization in order to achieve inference in a desirable manner.