As one on of the sciences of the Arabic Language, this research concentrates on the morphological criticism to al-Mutanabbi's poetry by a few ancient Arab critics who were not grammarians. The introduction presents the significance, aim and methodology of the research, then follows the talk of the aspects of the morphological criticism to al-Mutanabbi's poetry through highlighting the beginnings of the morphological and syntactic criticism. Building on this, it mentions the morphologically-criticized line of verse, records the criticism, and assesses this criticism based on the principles of syntax, morphology and the statements of the eloquent Arabs. Eventually, this research addresses the characteristics of this criticism, pointing out that such criticism carries heavy bias against Abu Tayyeb al-Mutanabbi. It neither utters the truth, nor is sincere; but tends to be envious and offensive, being follower of al-Basra school of syntax and morphology, and considering its opponents mistaken and faulty. It then mentions the important results is ends up with.