“On Practice” mainly is manifesting the Marxist philosophy candid spirit from four aspects: Looked from the philosophy sight, “On Practice” is the relative attenion “the life formula” philosophy; Looked from the philosophy function, “On Practice” is the attenion “the leader idea” philosophy; Looked from the philosophy faith and the mission that, “On Practice” is “lasts commits the ideas to paper” a philosophy; Looked from the philosophy development direction, “On Practice” pays attention to “the Chinese question” philosophy. The history is cannot cut off, if not truly understood “On Practice”, cannot truly understand Mao Zedong’s philosophy thought, also cannot to the Deng Xiaoping Theory, “three represent” the important thought and science development view has a more profound understanding.