“Muhammad ibn Othman” is the second representative and one of the pillars of the four representatives during the Minor Occultation and the mediator between Imam Mahdi (A.S) and the Shia during this period. The present research is seeking the answer to this question that how far and to what extent Muhammad ibn Othman impacted the confrontations with Imamate problems during the Minor Occultation; a period in which Imamate, on one hand, had faced the crisis of the absence of its Imam for the first time and on the other hand, encountered all types of social problems; in a way that the Imamate family has been attacked from all aspects. The present paper, with a library method, and using the analysis of historical data, investigates the life of Muhammad ibn Othman and explains this important fact that Muhammad ibn Othman behaved according to the various affairs of Imamate, one of the most important components in the field of legal representation, with his constant communication with Imam Mahdi (a.s). he acted according to Imam’s orders in receiving letters and religious taxes and delivering them to Imam or spending them, and had special role in dealing with the claimants of attorney and some disobedient lawyers.