High-Quality Development (HQD) can well meet human’s growing needs for a better life, and it is an important manifestation of efficient, fair and sustainable development. It is a crucial turning point for China from high-speed development to HQD. A better understanding the HQD from perspective of efficiency is very important for the development of China. Using prefecture-level city panel data of China from 2005 to 2019, this study built a model coupled with innovation, coordination, greenness, openness, sharing, and slacks-based measure (ICGOS-SBM) based on the Super-SBM model of slack variables. By introducing efficiency thinking, this study measured the HQD level of the Yangtze River Economic Belt (YREB, one of driving forces spearheading China’s HQD in a new era) from the perspective of development “quality”, and explored its spatial and temporal distribution characteristics. The results showed that (a) the temporal HQD levels of the YREB presented an “N”, pattern of rising first, then falling, and then rising; (b) the HQD levels exhibited noticeable regional heterogeneity a the different urban scale, and the development trend of the upper of YREB drove that of the middle and then that of the downstream; (c) the HQD levels of the YREB presented different degrees of spatial agglomeration, with an increasing trend over time, and the high-high agglomeration areas were mainly concentrated in the upper of the YREB with better natural endowments; and (d) the spatial HQD trajectory of the YREB mainly moved back and forth in the southwest-northeast direction, which may be due to its unstable development, showing a relatively obvious back-and-forth movement between Changde and Jingzhou. It aims to provide an innovative perspective for the measurement of HQD levels by introducing efficiency thinking.