In this paper, we present new reading of Nezami's Khosrow and Shirin based on concept of "desire" in Lacan's theory. And, also, we provide new definition of main characters and their positions. For explaining Lacan's desire, at first, the concepts related to this subject such as lost object, jouissance, differed action, drive and void are explained. After each concept, different parts of Mathnavi are analyzed with regard to that concept.In this inquiry, we conclude that the relation between Khosrow & Shirin and Maryam & Shekar is formed on the basis of search for "lost object". In the path of this search, Maryam & Shekar play the role of others (objet petit a) for Khosrow. Shirin represents Thing (das Ding) for Khosrow because of delaying of union, whereas after union lost object always remains lost and also search of Khosrow becomes endless.