Abstract：According to the state specifications for the first and second order leveling(GB/T 129872006), the methods and formulae for several corrections including correction of leveling staff for temperature, correction for normal nonparallel levels, correction for abnormal gravity, correction to solid tide and the load of sea tide, are given, and the necessity of those corrections for analysis and calculation of crustal deformation in seismic study are discussed. The results of this work emphasize that doing corrections or not must be the same for the new leveling data and old one in crust deformation analysis and calculation. If the old leveling data are not corrected, it is not necessary to correct the new ones. Otherwise, more unreasonable results may appear. For scientific research and multiple usage of leveling data, it is suggested that all the accessorial observation data in every leveling correction should be preserved completely in seismically leveling.
