Abstract: China's local government cooperation is faced with the problems of lack of legal basis for the exercise of crossregion administrative power,restriction of power allocation on regional collaborative legislation,power effectiveness loss,and poor implementation of policies. The fundamental reason is the mutual constraints between politics and law,so it is necessary to re-examine the relationship between politics and law and understand their functional characteristics. In the framework of system and environment interpretation, politics and law are social subsystems with power and legislation as the core, which operate separately and have differentiated functions. Governmental administrative agreement is used as the channel between systems to maintain boundaries and form specific connections. The external environment stimulates the system through this special channel, and the system accepts useful information through independent selection, so that the system itself and the external environment continue to adapt. This process illustrates the formation of the coupling relationship between political and legal structures in the current local government cooperation in China. The formation of this relationship can provide a reasonable basis for the cooperation of local governments and promote the continuous perfection of the legal function.

Key words: local government cooperation, political system, the legal system, structural coupling, Luhmann social system theory, administrative agreement