This paper seeks to offer some prescriptive criteria for assessing,reforming, and selecting various electoral systems. In doing so, the author briefly describes classification of electoral systems, comparatively reviewing of various electoral systems in the world. Criteria such as effectiveness of the state, accountability and responsibility of the state, observance of justice with regard to small parties, and so on might be opposite criteria, so that there is a trade-off between them. Then, the author studies the consequences of selecting a special electoral system,mentioning effect of choosing electoral system on party system, observance of proportion in appropriating votes to representatives,establishing one-party or coalition government as well as on participation in election and social representative. With suggesting that performance of electoral system has some consequences, this paper concludes that perhaps there is no "best" electoral system, and pros and cons arguments on an electoral system indicate some un-resolvable normative conflicts, even though the choosing a special electoral system in any society completely depends on intellectual, cultural, and political backgrounds of the society