The　time-frequency　method　of　wavelet　transform　was　used　to　analyze　the　ground　motion　at　offshore　site.　The　acceleration　records　of　the　offshore　site　ground　motions　were　collected　from　California,　U.S　and　Sagami　trough　zone,　Japan,　and　decomposed　into　six　layers　of　wavelet　packets　by　Matlab　software.　The　energy　spectrum　on　the　different　sub-bands　and　time-frequency　distribution　characteristic　of　acceleration　records　were　analyzed,　simultaneously　contrasted　with　the　outcome　of　records　collected　from　the　closed　sites　on　the　coast　and　recorded　from　the　earthquakes　in　land,　like　Wenchuan　earthquake　and　Lushan　earthquake.　The　energy　of　the　ground　motion　at　offshore　site　was　concentrated　in　the　primary　8　sub-bands.　Meanwhile,　the　low　frequency-band　was　dominant　in　the　frequency　range,　which　was　different　from　that　of　the　closed　sites　in　the　land.　However,　the　energy　of　ground　motions　in　land　has　significant　distribution　in　high　frequency　region.　The　horizontal　and　vertical　ground　motion　at　offshore　site　demonstrated　the　wide　band　characteristic　of　energy　distribution,　while　the　energy　of　the　vertical　ground　motion　at　inland　site　is　far　less　than　that　of　the　horizontal　ground　motion.　In　the　time　domain,　the　energy　showed　obvious　secondary　released　phenomenon.　©　2016,　Editorial　Office　of　China　Civil　Engineering　Journal.　All　right　reserved.