Engels’ attitude to Das Kapital was to regard it as the unity of scientific work and historic work, upheld to raise “historic character” from “scientific morality”, which is the explanation of materialism path. Furthermore, Engels overall demonstrated his dialectic method of analysis, the common ideology with Marx, to construct “great logic” by his hard work. There are three clues between Engels’ work and the method of Das Kapital, firstly he associated the research on Natural Dialectics with the chapter of “commodification” in Das Kapital, hoping to completely eliminate “Proudongism” in Marxism theory, then he insisted on Das Kapital from “natural process” to “historic process”, theoretically interpreted it from total methodology and theoretical logic to natural historic process based on the working logic of embryology. The third part is Engels’ consideration on historic materialism during his late years, which promoted supplement to Das Kapital and made great cognitive advance. As a result, he made great epistemology boost. In other words, from extensive angle, Engels tried to view Das Kapital as an overall preview of the “Dialectic Method of Analysis”(Dialectics of Materialism), which Marx should have finished by himself. Based on Engels’ hard work on “dialectic method of analysis” with materialism, Das Kapital gradually becomes the weapon to guide scientific thinking and the fighting weapon in ideology, which lays the stable foundation for “Russia localization” and “China localization” of Das Kapital.