With the use of the 1985～2008 monitoring data of ground subsidence in Tianjin City, and by thoroughly analyzing the leveling bench marks and their subsidence movements in time, the paper uses the piecewise weight function linear model to extract subsidence information and extend forecast and then study the current status of ground subsidence in the whole area. On the basis of the current status and its development tendency, the distributions of ground subsidence isoclines in Tianjin Binhai New Area of 2008 and 2008～2013 are given, which can be references for the governmental countermeasures and for some other similar areas.