Using the data of early 1999 to September, 2010 from continuous stations of the Project of  “China Crust Movement Measuring Network”, this paper analyzes 90 GPS baseline time series of continuous stations in the mainland of China. Firstly, the authors discussed the tendency variation characteristics of all these baselines under the normal condition, and then summarized the abnormal changes of GPS baseline time series before two strong earthquakes. Finally, recent variations of GPS baseline time series have been analyzed