Abstract: Vertical crustal displacements of the Earth's crust in China,due to atmospheric loading effects,are assessed by a spherical harmonic expansion method.The results show that the vertical crustal displacements range up to 20~30 mm,predominantly at the seasonal time scale.The comparison between the seasonal time series of atmospheric loading and the observed GPS daily heights for the six GPS fiducial stations in China indicates that atmosphere is the main cause for the seasonal vertical displacements of the Earth's crust.