Modern information technology networks have changed people’s production and lifestyle, leading to new changes in the economic structure of capitalist society and bringing new challenges to the use of Marxism to criticize capitalism. Based on the knowledge of Marxist economics, this paper provides a critical overview of the changes in the economic structure of capitalism from two aspects: the changes in the forms of capital exploitation and the expansion of capital exploitation relations. Using the complex network theory in modern information technology, a capitalist socio-economic model is constructed to perform a critical quantitative analysis of the structural changes in the capitalist socio-economic structure. A case study of capitalist socio-economic structure is conducted in conjunction with the previous model. The results show that the entropy of capitalist wealth E is decreasing in the case that the parameters of N = 1000, m = 6, and M = 40 are determined, and the traditional labor distribution system and production mode will be eliminated by history in the end. Through a critique of capitalist economic mechanisms, it deepens people’s knowledge of capitalist economic structure.