This publication attempts to examine the implementation of the principle of ideological diversity in the law on political parties. The article emphasizes that the principle of multi-party system on the one hand acts as a guarantee of the implementation of the rules of the ideological diversity, and on the other hand, political parties are one of the main subjects of the constitutional law, realizing the right to ideological diversity. It has been shown that one of the most significant shortcomings of the Russian party system is the existence of the dominant party, including representatives of legislative and executive power. Based on the analysis of the current legislation the author established that by consistently transforming the legal framework governing the establishment and activities of political parties in the direction of the changes in the electoral law relations, and legal regulation of the method of distribution of seats in Parliament, and by settling legal mechanism for opposition activities, one can extend the limits of the general state and legal realization of ideological diversity in the Russian Federation.