The Yangtze River Economic Belt represents a key driving force behind a new development paradigm in China. Fostering a new paradigm requires the creation of a single market among the three city clusters across the Yangtze River Economic Belt. Field research and statistical analysis have found that the market integration level and market integration process of the three city clusters along the Yangtze River Economic Belt show obvious tiered differences，highlighting the constraints from differentiation in integration. It is urgent to take a cluster-by-cluster approach and holistically advance the process of market integration across city clusters. The goal is to see that the Yangtze River Economic Belt will emerge as a poster child for collaborative development.