In fact any new thought or idea is originated from a new perspective or experience and to express a new thought, a new language is needed and simile is the manifestation of thought and the way of thinking, imagination and the experience of poet, the representation of his ability in creating a harmony between parts, the internal and external nature and also the relation of creatures with the environment. Thus, simile in its comprehensive meaning is the cause for the changes in styles in all artistic fields specially the poetry so its analysis can represent the personal style of the poet. Attar used various expressive elements, especially simile for the expression of thoughts and spiritual concepts. According to authors of this paper, this work hither to, has been analyzed from different aspects. But few if any have done research on the simile and its various structures in this work. This study while making the readers familiar with various forms of simile in Asrarnameh, aims to investigate the status of simile in the expression of Attar's thoughts. The basis of this paper is presenting a structure according to the introduction and analysis of different kinds of similes and their structures in terms of used elements and materials, sensory and intellectual sides, compression and expansion of the structure, single and complex structure, form structure and vehicle, and methods are based on the description and analysis of the data, from the perspective of rhetorical modes. Is also at the end, based on statistical samples, the status of simile types have been shown in Attar's Asrarnamh. Doing this research we find that simile at Asrarnamh is an important expressive element for the expression of Attar's ideas and is used in a variety of forms and structures.