This paper aims to investigate Arabic word classificationbased on Arabic Grammarians and modern linguists’perspectives and principles which they use in thatclassification. As it is explored by Arabic Grammarians, theword classification is divided into three components, suchas ism (noun), fi'l (verb) and harf (particle) ,which causesproblems when between definition and sign of each of theclassification is unmatched in a given text. Therefore, somemodern linguists, one of them is Tamām Hassān, try toreconsider and to remake a new classification of Arabicwords. While other Arabic Grammarians only use the sixprinciples of classification (such as distribution principle,substitution principle, function principle, morphemeprinciple, meaning principle and predicative principle),Tamām Hassān uses two additional principles, those are:the form principle (al-mabnā) and the meaning principle (alma'nā).and the conclusion of is that Arabic word is divided to seven such as ism (noun), sifah (adjective), fi'l (verb),damīr (pronoun),  arf (adverb), khalīfah (exclamation) andadāh.