Since the reform and opening-up in 1978, the morphology of urban built-up land (UBL) has been changed significantly due to the rapid socio-economic development in China. Moreover, this change shows an unbalanced variation over space. Based on the UBL area and census data from 1981 to 2015, we use the moving T-test, kernel density estimation and Gini coefficient to identify the abrupt change points over UBL transition process and present its dynamic spatial pattern. This research exhibits four main results. First, there are three identified stages over the transition process, namely, low expansion rate of UBL-decrease of per capita UBL (1981-2000), moderate expansion rate of UBL-slow increasing rate of per capita UBL(1990-2000) and high expansion rate of UBL-high increase of per capita UBL (2000-2015). Second, the spatial pattern of UBL area transition proceeds slowly over the periods of 1990-2000 and 2000-2015. Cities with a high expansion rate of UBL tend to present a spatial pattern of an agglomeration over the Yangtze River Delta and the Pearl River Delta, and the rest of the regions that tend to show a spatial pattern of an dispersion are provincial capitals in the central and western regions. On the contrary, cities with a high increasing rate of per capita UBL tend to originate from the eastern region to the entire country. Third, the variance of the UBL tends to be smaller during 1990-2000 and then greater during 2000-2015 over space, while the variance of the per capita UBL tends to be smaller during 1990-2000 and then stable during 2000-2015 over space. Lastly, we find that the results correspond to the previous theory of regional land use transition, and the socio-economic transformation phenomenon demonstrates the three identified stages. Moreover, the transition of spatial pattern reveals the fact that the change of national development strategy is from the priority of eastern coastal areas to the regional coordination. This work fills in a gap of quantifying the stage of land use transition, and provide support references to UBL management in the socio-economic transformation in the new era.