Abstract: In this paper, the correlation adjustment method for deducing shear strain rates directly from repeated geodetic data is studied. The criteria for reliability assessment of the calculated results of land deformation are briefly discussed, and the differences between the calculated results by the correlation adjustment method and that by conventional method compared. The results of actual calculation for several regions surveyed suggest that in order to monitor the horizontal crustal movements in large areas it is entirely necessary to improve the accuracy of geodetic survey to a high degree for seismological work.