The model of dual - nuclei spatial structure is a new style of spatial structure. It is generally found in the coast belt , the region of Yangze River in China and abroad. This paper uses the theory of model of dual - nuclei spatial structure to analyze the formation of ChengYu dual - nuclei and points out that Chongqing and Chengdu are typical model, which have specific characteristics. The economic character of dual - nuclei spatial structure determines the competition between dual - nuclei cities. By analyzing the history and present situations of competition and cooperation between ChengYu dual - nuclei, the author points out that the development of ChengYu dual - nuclei needs to cooperate in competition environment and to compete benignly in cooperation environment, at last, gives some suggestions about how to improve the cooperation between ChengYu dual - nuclei.