The cyclic iteration of think tank research reflects the continuous iteration and rapid progress in cognition, reflecting the inherent law of cognition. Think tank research is also an evidence-based science that rests on multiple rounds of evidence-based argumentation on research problems. Revolving the think tank problem, data and information are collected to generate research results with reliable evidence and credible conclusions, which reflects the process of cyclic ascension, deep convergence and repeated evidence-based argumentation. This chapter focuses on cyclic iteration, a key issue of think tank research, and elaborates on the connotation and significance of cyclic iteration in think tank research. In addition, the triggering situations and stages involved in the cyclic iteration of the Double Helix Methodology in Think Tanks are analyzed. In the end, the cyclic iteration process of Double Helix Methodology in Think Tanks is proposed, and the application of the cyclic iteration process in practice is illustrated through cases.