Monitoringofsubsurfacefluid(undergroundfluid)isanimportantpartofeffortsforearthquakepredictioninChina.Thenationwidenetwork,whichmonitorsgroundwaterlevel,watertemperature,andradonandmercuryingroundwater,hasbeenconstructedinthelastdecades.Largeamountsofabnormalfluidchangesbeforeandaftermajorearthquakeshavebeenrecorded,providingpreciousdataforresearchinearthquakesciences.Manystudieshavebeendoneinearthquakefluidhydrogeologyinordertoprobethenatureoftheearthquake.Muchprogressinearthquakefluidhydrogeologyhasbeenmadeinthelastdecades.Thepaperprovidesareviewoftheadvancesinresearchonearthquakefluidhydrogeologyoverthelast40yearsinChina.Itdealswiththefollowingfiveaspects:(1)anintroductiontothedevelopmenthistoryofmonitoringnetworksconstruction;(2)casesofdifferentsubsurfacefluidchangesrecordedbeforesomemajorearthquakeswhichoccurredinthelastdecades;(3)characteristicsofsubsurfacefluidchangesfollowingmajorearthquakes;(4)mechanismofsubsurfacefluidchangesbeforeandfollowingearthquakes;(5)applicationofearthquakefluidsinthehydrogeologyfield.
