The research consists of an introduction that includes a brief definition of poetic rhythm and its forms and defines prosody as a system of syllables in the speech movement. It is also a system that is based on different syllables and their suitability and repetition in the poetic line as well as the qasiad (poem). The research also reviewed the development of prosodic structure within the requirement of the development of the Arab poetic discourse. This development occurred via three forms that each form prevailed a certain stage of the stages of the Arab poetic discourse. The first form is the stiff or static form that was materialized by the single metre and monorhymed qasiad (poem). Then, the diversified form that was materialized by the romantic qasiad (pem) characterized by diversification of poetic line, metre and rhyme. The final one is the dynamic form materialized by the modern qasiad (peom) that is based on the poetic line that does not abide by a certain engineering of phonetic structure, semantic structure or visual structure. The research also reviewed the aesthetic impact of prosody through three functions: the function of tension that is based on the principle of contradiction between phonetic structure and semantic structure. The function of (Music disorder) that is based on the suitability of phonetic structure and its repetition. Finally, the function of expression that is based on diversifying prosodic structure according to the requirements of the semantic structure. The research conclusion confirmed that prosodic structure was not stiff or static but evolved within the development of the Arab poetic discourse.