Adetailthree-dimensionalPwavevelocitystructureofBeijing,TianjinandTangshanarea(BTTarea)wasdeterminedbyinvertinglocalearthquakedata.Intotal16048Pwavefirstarrivaltimesfrom16048shallowandmid-depthcrustalearthquakes,whichoccurredinandaroundtheBTTareafrom1992to1999wereused.ThefirstarrivaltimesarerecordedbyNorthernChinaUnitedTelemetrySeismicNetworkandYanqing-HuailaiDigitalSeismicNetwork.Hypocentralparametersof1132earthquakeswithmagnitudeML=1.7~6.2andthethree-dimensionalPwavevelocitystructurewereobtainedsimultaneously.TheinversionresultrevealsthecomplicatedlateralheterogeneityofPwavevelocitystructurearoundBTTarea.Thetomographicimagesobtainedarealsofoundtoexplainotherseismologicalobservationswell.