Abstract: The traditional OODA（observation-orientation-decision-action）ring theory has such shortcomings as low cognitive granularity,one-way circulation, and single entrance, etc. and can't meet the multi-domain joint combat requirements with intelligent, networked,systematic features and isn't capable of applying in the complex decision-making environment represented by multi-domain coordination, systematic optimization, etc. Based on the sorting out and analysis of the development process and the evolution route of OODA ring theory, the focus of OODA ring theory for complex decision-making is determined to highlight the role of cognitive links and decision-making links in the whole OODA ring. By analyzing the empowerment mode of intelligent technology, the intelligent situation cognition and intelligent complex decision-making framework are constructed, and these two frameworks are embedded in the OODA ring with increased cognitive granularity to form an intelligent CT-OODA ring theory for complex decision-making. Based on Cynefin theory, the environmental classification method of complex decision-making problems is explained, and the operation mode of intelligent CT-OODA rings in decision-making environments of different complexity is elaborated, and how the dynamics of decision-making environment change are realized through OODA decision-making circulations. An intelligent OODA for complex decision-making and its specific structure and operation mode are proposed,and a method for classifying complex decision-making environments is proposed, to provide reference for future human-machine fusion situation cognition and complex decision-making.