By using the 1∶100 000 landuse vector data in the three periods of the middle 1980s

1990s

and 2000 which are provided by Data Center for Resources and Environmental Sciences

Chinese Academy of Sciences

and by taking GIS as charting and analysis method

the relationship between the space and time changes

the shape characteristics of urban land expansion

and the pop ulation and economics development in Tianjin City were analyzed

Such indexes as urban land expansion velocity and intensity

centre coordinates

compact ratio

fractal dimension

and elasticity coefficient were used in the analysis.It was revealed that the spatiotemporal variation of Tianjin urban land from middle 1980s to 2000 was obvious and that the Tianjin northwest southeast axial and the coastal axial were the mostactive expansion parts.The construction land expansion has been transforming to the irrational direction.The area—GDP elasticit y coefficient was raised and the annually averaged change ratio of economy exceeded far from that of urban expansion.Finally

the brief effect of urban expansio n was the lost of cultivated land and other land resources around the city.The contributio nof cultivated land to the overall urban expansion area was largest and the contribution of other lands such as forest land

grassland

water area

and not using land was second.