Das Kapital is a brilliant masterpiece of proletarian political economy and an encyclopedia of Marxism. Lenin pointed out: "Marx thought that the economic system was the foundation on which the political superstructure was built, so he paid special attention to studying this economic system. Marx's main work specializes in the economic system of modern society, that is, capitalist society. " Marx devoted himself to the study of political economy. His criticism of political economy and Das Kapital "completely changed the science." There are many versions of Das Kapital. When Marx and Engels were alive, each edition had a preface or postscript. These prefaces and epilogues constitute an indispensable part of Das Kapital and become an introductory guide for us to learn Das Kapital. The first volume of Das Kapital has seven prefaces and epilogues, the first four of which were written by Marx himself and the last three by Engels. In the preface and postscript of these seven articles, the most important ones are the preface and postscript of the first edition and the postscript of the second edition. In these prefaces and epilogues, many important issues of Das Kapital are discussed. For example, about the writing and publishing process of Das Kapital, about the research object and purpose of Das Kapital, about the method and structure of Das Kapital, about the class nature of political economy, and the problems needing attention in studying Das Kapital, etc.