Abstract: According to the hydrogeological condition of limestone equifer of Ordovician system at the northwestern wing of Kaiping syncline in Tangshan City, the recharge quantity of aquifer groundwater is calculated according to the isostatic computational principle and the amplitude of water level variation is analyzed by groundwater recharge quantity.The relatively large variational amplitudes of water level of No.05 and No.08 wells of the Seismological Bureau of Hebei Province are calculated,there is little difference between the comparatively calculated value and the observed value, which shows that the variational value of water level is caused by the variation of aquifer recharge and discharge conditions.