This study shed the light on the sensory homogeneity phenomenon " Synesthesia"  by presenting the scientific definition for it, and applying it in the literary work of Baudelaire. This paper will present how this neurological and physiological phenomenon passed successfully to art domains, not just in  theater and in music, but it went beyond to literary field. In fact, Baudelaire was one of the first who believed in this phenomenon. He found it a rich source for inspiration, and a first step toward a modern literary revolution for the French poem. Therefore, the French poet created , by this theory, his own aesthetic theory" The Correspondences", which sees the human senses beyond its main function and aims to mix them, all this to  arrive to idealism in expression and to pave the road toward symbolism which Consider  Baudelaire one of its pioneers loyal.  However, the poet has a strange intuition in this area. He starts to study every things psychologically and to  establish a network, on the one hand,  between the reality and the symbol, and on other hand, between the past and the future to connect the poem to the immortality What is Synesthesia? How did our poet develop this sensory phenomenon of physiological origin into a wonderful color adorned by the French poem and boasted through the ages? How did he benefit from the previous sensory theories in his work? And, finally, how did he treat this sensory phenomenon in his poetic works?  We will try to answer to all of these questions with an amount of exceptional examples from  literary production of Baudelaire