Abstract: Objective Estimation of processes for slow change in small scale surfaces is one of the main advantagesof PSInSAR technology.We present a mathematical framework for the datum connection for time-space referencing,applying it to 500scenes composed of Envisat ASAR images covering about 200 000km2 of the North China Plain,obtained the rate of ground subsidence in the study area during the pe-riod of 2006-2010.The experimental results show that:(1)the multiple subsidence centers in NorthChina Plain were still in an evolving state,connecting Beijing,Langfang,Tianjin,Renqiu,Cang-zhou,Botou,Hengshui,Dezhou,Nangong and Handan into a continuous area.(2)The most promi-nent ground subsidence was in Tianjin’s Jinghai and Binhai areas having average subsidence rates of62mm/a and 67mm/a along the line of sight,respectively.The subsidence of the old centers,to theeast of Beijing,Cangzhou,Botou -Hengshui -Dezhou,Handan,had rates of 36mm/a,34mm/a,37mm/a,29mm/a,respectively.(3)The experimental results were validated with leveling data inTianjin area.The difference between the two methods is less than 10mm,which shows that the re-sults obtained by the PSInSAR technique are consistent with those obtained by leveling.(4)The re-sults here presented can be used as development prevention reference measures of regional ground sub-sidence.