Abstract: The scientific level of party building is affected and restricted by the degree of intra-Party democracy. In history and reality the Party's understanding of intra-Party democracy has been constantly intensified with historical evolutions of revolution, construction and reform. And also, there have been many important ideas of building up intra-Party democracy, in theory as well as in practice. From the elements of Party life, democracy and science are closely linked. The mechanism of their relationships shows an internal unity of promoting intra-Party democracy and making Party building more scientific. And from the goals of building a Marxist ruling party, the intra-Party democracy and scientific Party building are also consistent. The only way to improve the scientific level of Party building is to promote intra-Party democracy. They are all the requirements of building a Marxist ruling party. To make Party building more scientific, it requires building intra-Party democracy within the precondition of Party development, forming scientific ideas of intra-Party democracy, improving scientific methods of intra-Party democracy and institutionalizing the intra-Party democracy building.

Key words: Party building , intra-Party democracy , scientific level