Cheng-Yu Economic Zone is economic nucleus of the Upper Reaches of Changjiang River,its core is a city cluster based on center cities of Chengdu and Chongqing which are composed of city group of Chongqing,city ring of Chengdu,economic band combined Chengdu-Neijiang(Suining)-Chongqing,city band combined with Chengdu-Deyang-Mianyang and city group distributed in South Sichuan.The key to forming Cheng-Yu Economic Zone is Chengdu-Neijiang(Suining)-Chongqing Economic Band whose formation must possess three conditions such as plan organization of upper level government,building of rapid speed railway traffic and development of city group distributed in South Sichuan.