With the continuous development of industrialization and urbanization，the scale of urban construction land has been expanding，which had caused the agricultural land declining sharply，environment degrading，land no-intensive using，and so on. Accompanied by the publishment of The Development Plan of Jiangsu Coastal Area，the development of the Jiangsu coastal area had being into the fast lane. As the construction land is an important resource of the city development，the reasonable control of its expansion，the scientific developing plan of the land had becoming urgency. Used the panel data of the 23 counties in Jiangsu coastal cities from 2011 to 2015，this paper researched the dynamic evolution characteristics and spatial differences of the construction land expansion in Jiangsu coastal cities. In this process，the city construction land expansion rate was the index，and the Gauss Kernel density estimation，Gini coefficient decomposition，Markov chain method，etc. was be used. The results showed that：（a）During the investigation period，the expansion rates of the construction land in Jiangsu coastal cities slowed down，and the internal differences were gradually reduced，accompanied by the phenomenon of polarization. The characteristics of the construction land expansion in Nantong，Yancheng and Lianyungang were not same，but the basic trend was “south high and north low”.（b）During the investigation period，the Gini coefficient of the urban construction land expansion in Jiangsu coastal cities was decreased firstly and increased subsequently. The inner Gini coefficient of the investigation region was decreasing successively in Lianyungang，Yancheng and Nantong. The Gini coefficient between regions was changing during the investigation period，among which the difference between Nantong and Lianyungang was the biggest. The intensity of transvariation was the main reason which caused the spatial difference of the construction land expansion in Jiangsu coastal cities and its contribution rate was been increasing. By contrast，the contribution rates of inner Gini coefficient and the Gini coefficient between regions were shrinking and tending to be consistent.（c）In the future，the probability that the construction land expansion would be medium or low velocity was large，which indicated that the phenomenon of the land was be extensive used tended to be eased. Based on the above research conclusions，this paper put forward some useful inspirations to contain the rapid expansion of the construction land and promote the efficiency of the land using.