Abstract: This paper collects the sustained land data from the Department of Homeland, for studying the influence of scale change on urban expansion. We extract urban land for the corresponding annual central city by using ArcGIS10.2 software, and then change the data scale from 50m to 1000m and take 50m for the step size. The urban expansion scale, fractal characteristics and expansion model are analyzed in different scales. It shows that 350 m is the optimal study scale. Based on optimal scale, the characteristics of urban land expansion from 1996 to 2014 are studied. The results show that: (1) Expansion rate of 1996-2005 is obviously higher than 2005-2014. Its scale is in accordance with industrialization and urbanization period.(2) The type of expansion acts as obvious periodicity and regularity. Early expansion mainly includes spread expansion and enclave expansion, and then significant filling expansion emerges. There are gradient moves in all directions. (3) In the past 20 years, the urban fractal dimension has been growing. Convex graphics indicates that the city center would expand again in the future and has been becoming more complex. In the last part of this paper, we provide some suggestions for the management of urban expansion, and expected to make references for the similar regions or studies.