Abstract: Based on the results of GPScontinuous observations at the fiducial stations in theCrustal Movement Observation Network of China(CMONOC) from early September 1998 tothe end of June 2002 and combined with the time series of the displacement components aeach station, the authors have tried to discuss in a conceptually direct and clear way on the ac-curacy of the horizontal crustal movements, the stability in the horizontal position of the monu-ments of the fiducial stations in CM(DNOC and the temporal and spatial evolution of the hori-zontal crustal movements before and after the great Kunlun mountain earthquake with M8. 1on Nov. 14, 2001.

Key words: Crustal movement, GPS, Time series, Great Kunlun mountain earthquake with M8.1, Displacement vector