School of Marxism Studies, Wuhan University, Wuhan 430072, China)Abstract: Mao Zedong s thinking on keeping the Party s purity is derived from the great practice of the Party s mass line, and it is also the scientific summary of practical experience of the Party s mass line, which, in turn, guides the social practice of the Party s mass line. The inner unified relationship between the unity of Mao Zedong s thinking on keeping the Party s purity and the Party s mass line mainly includes: it adheres to seeking truth from facts, objects to bookishness, reflecting the unity of value and truthfulness; it adheres to the arduous struggle, objects to hedonism, reflecting the unity of ideal and reality; it adheres to the Party s unity, objects to the Party s partition, reflecting the unity of goal setting and practical situation; it adheres to keeping close ties with the masses, objects to formalism and bureaucracy, reflects the unity of finality and instrument; and it adheres to the truth, objects to fallacy, reflects the unity of transforming both the objective world and subjective world. This relationship has played a fundamental guiding role in the construction of the purity of the Communist Party of China and the education of the Partys mass line in various historical periods.