Abstract: The duality of labor-management exchange and its paradox of justice are important aspects of Marx's capitalist critique. In Marx's view, capitalist labor exchange is divided into two processes, among which the first one is about the exchange of general commodities with equivalence, and the second one is about the “exchange” of labor commodities with inequality. In the process of labor exchange, freedom, equality and ownership, which characterize capitalist justice, go to their opposite and present a paradox. Therefore, if one considers capitalism as just based on the equivalence of labor exchange, one will fall into the “harmony theory” criticized by Marx; if one considers capitalism as unjust based on its inequality, one will make the mistake of general economists who regard labor exchange as a result rather than a process. Only by analyzing the economic relations in labor exchange and determining the justice of capitalism through the connotation of equality, freedom and ownership in it can the interpretation of labor exchange not go in the direction Marx criticized and the path of Marx's construction of justice be found.