Landuse structure and spatial form changes are studied for the central areas in Shanghai from 1947 to 2000. Based on the systems and the fractal theories, the information entropy and equilibrium degree of landuse structure are calculated and the fractal models of urban spatial forms are established for Shanghai.  The main conclusions are: (1) In the past 50 years, the information entropy and equilibrium degree of landuse structure of Shanghai are increasing gradually, the differences in areas of each landuse type are reducing and the urban landuse structure are approaching to equilibrium state. (2) Boundary dimensions of landuse form have been decreased and the boundary forms of all the landuse types changed more regular and smooth since 1996. (3) Based on radius dimension, an annular spatial form from residential area to industrial area and to farmland according to distance away from city center is established.  In the end, we summarized mechanism of landuse change as population explosion, science and technology advancement, economic growth, policy and society systems changing and so on.