Many of first-hand accounts of Shi’a sources, and some of the Sunni traditions have mentioned the apparent of age of Imam Mahdi (A.S) at the time of Appearance and said he would be 30, 32, 40 and less than 40, or about him, different interpretations such as Servant (Child), Shaab (Youth), Shaab Hadith (Youth in his early juvenility), ShaabMovafagh (Successful and Perfect Youth), Fatta (the Perfect Man) have been used. Although apparently, these traditions have different interpretations which have been used as subterfuge by Baha’i, especially by Abolfazl Gulpaygani in the book “Faraa’ed”; with a careful attention in the signification of traditions and their analysis and examinations and the interpretation of words and their usage in Arabic, in addition to the traditions about the Imam’s lifetime, the lack of conflict and the unity in all traditions’ theme becomes clear and clarified and all the traditions indicate that Imam’s lifetime has no impact on his appearance and he will appear in his youth.