Abstract: Based on water level coseismic observation data in Hebei well-21 from January 1, 2016 to December 31, 2017of M ≥ 6 mainland earthquakes and M ≥ 7 global earthquakes, the morphological characteristics and seismic recording ability of the coseismic effect in the well water level were studied. The result show that the water level is sensitive to the record of large earthquakes in the far field (the surface wave in the longer wave band). The waveform frequency range recorded by well-aquifer is summarized to provide basic information for anomaly analysis of observation data.