This article analyses the evolution of party system and parties in Denmark during 20th century. Special attention is concentrated on the phenomena of freezing and unfreezing of party system between 1920s and 1960s. However, unfreezing of the party system, which was demonstrated by election 1973, led to the explosive and massive increasing of number of parties, the system (type) change was temporary. Is it true that format of the limited pluralism was transformed to the extreme pluralism. But the type of the party system came back to the earlier moderate pluralism in 1980s. Similarly as in the other Western European countries, the organisation of Danish political parties has changed: from the mass parties with close linkage to some social class and with joining to interests groups (the best example was the social democratic party and trade unions), to more open formation with the catch-all features. A look of the party system was influenced by the new political issues as well. The special importance had the membership in the European Community, immigration issue, postmaterialistic values, reform of the welfare state (and progressive tax) and revitalisation of the church-state division. However, the traditional right-left axis keeps its significance.