"JIAN AN"is the reign title of the LIU XIE,which is the last emperor of the Eastern Han Dynasty.The time span of"JIAN AN"is from A.D.196 to A.D.219.The meaning of it is disputed in the history of literature,and there isn’t final conclusion.The author of this article summarizes many different opinions from other scholars and specialists,and comes up with his own viewpoint about the time span of literature,JIAN AN.We consider that the time span should be from A.D 190 to A.D.239.