Political parties are of the most important political organizations which affect directly the movement of political system and guarantee its and stability and continuousness .They play an important role in activating political life . And they became an essential aspect of democratic systems . Performance of parties has it reflections positively or negatively on the quality of political life and on the level of democratic development and political modernization and activity of political system which is considered a reflection of the parties system that is dominant in the state . Political parties have an important role in making public policy and framing it as they are channels of political partnership of citizens, and organized political communication in society . Policy scientists consider them the strong organized basis for the connection of summit and base and a communication station which is necessary between citizens and authority .This study is an attempt to acknowledge public society which is a difficult and complex political process . The nature and procedures of its shaping differ from a state to another according to political system and the role of government and non-government entities and political parties are of them . The research deals with the role of political parties in shaping the public policy of the state , planning , execution and evaluation , by looking at their role in planning the public policy of the state mainly throughout their presence and representation in the legislative authority. And also by highlighting the role of parties in implementation of public policy throughout sharing in the executive authority and the volume of this partnership. And also knowing the role of parties in the process of evaluation of public policy, because actual, active and objective evaluation is the basis of the success of public policy in achieving its goals .The study finds out that parties can plan , implement and evaluate public policy, if they reach authority and in consequence they shall apply their programs via laws which they enact in (Legislative authority) or by implementation of laws in (Executive authority – Government)or by their presence in opposition and here they may use many methods and ways to exert pressure on and affect authority.