Political economy is an important part of Marxism. It is a science that studies the relations of production and its development law in human society. In the process of studying political economy, Marx discovered the general law of the development of human society and formed the historical materialism. Once discovered, historical materialism and dialectical materialism together as a scientific world outlook "guide" Marx's "research work". Marxism has deeply studied the capitalist relations of production, "revealing the secret of capitalist production through surplus value." The masterpiece Das Kapital makes Marxist political economy the only scientific political economy. Marxist political economy provides scientific proof for Marxist philosophy in the field of social sciences and enriches the scientific methodology of Marxist philosophy. Marxist political economy has also laid a solid theoretical foundation for scientific socialism.