The booming development of the digital economy has sparked debates on “digital labor”. To accurately grasp the nature of “digital labor”, we must return to Marx’s theory of productive labor. In Marx’s view, the “productivity” of labor is first and foremost relative to capital, and productive labor belongs to a “process of force” that follows the law of material transformation. In a society dominated by the capitalist mode of production, productive labor should be defined as wage labor that assumes production functions in the process of social reproduction. The theoretical disputes surrounding the theory of productive labor arise primarily for the following reasons. First, Marx progressively deepened his study of social reproduction in a broad sense in his research, leading to the lack of a clear and unified definition of the concept of productive labor in the classic texts of different periods. Second, the rapid development of service sectors in modern society has obscured a comprehensive understanding of the theory of productive labor. Third, the theory of productive labor potentially contains doubts about the rationality of non-productive labor, carrying socio-critical implications that provoke instinctive opposition from defenders of the existing order. Only by clarifying Marx’s theory of productive labor can we grasp the true essence of the surplus value theory of the labor value theory. Additionally, adhering to Marx’s theory of productive labor has important practical significance for promoting healthy socio-economic development. From a practical perspective, it is imperative to monitor changes in the employment structure of the working population in real time, comprehensively evaluate the socio-economic effects of the development of the service industry, and advance the construction of a reasonable “division of labor-distribution” order.