Abstract: The deepening of the new round of scientific-technological revolution is profoundly affecting and transforming the way of social living and production. The social system is evolving into a complex system coupled with human social space, information systems, and the physical environment. In the social system, actors, social relations, social structure, and social functions are profoundly changing. Human beings are entering a new social form characterized by the integration of human and machine. Such changes have brought significant challenges to the understanding, research, and governance of social systems. The definition of the human-machine integration social system is expounded from the perspective of the social system theory. It analyzes the unique connotation of human-machine integration complex social system from the aspects of social constituent subjects and structures, communication and media, and social differentiation and evolution. On this basis, the basic problems that need to be solved urgently in the research of human-machine integration complex social systems are proposed: (1) Human-machine collaboration in human-machine integration complex social systems; (2) Social networks in the environment of human-machine integration; (3) Emergence mechanism and evolution law of human-machine integration complex social system. Finally, aiming at the difficulties faced by previous social science research methods in solving the integrity problem of complex social systems, a research paradigm of complex social systems based on the system theory is proposed.

Key words: complex system theory, human-machine collaboration, social network, emergence mechanism and evolution Law, complex social systems