In　this　work,　experimental　studies　on　liquefaction　of　saturated　sand　were　carried　out　under　confined　condition　by　using　geotechnical　dynamic　true　triaxial　apparatus.　Based　on　the　analysis　of　stress　time-history　curves　and　effective　stress　path,　it　is　found　that　in　cyclic　loading　test　under　confined　condition,　the　pore　water　pressure　and　confining　pressure　may　change　synchronously　and　equivalently　with　axial　dynamic　load,　and　that　the　generalized　shear　stress　and　mean　effective　principal　stress　always　remain　at　liquefaction　stress　level　after　the　liquefaction　is　initialized.　Based　on　the　above　phenomena,　the　concept　of　＇continued　liquefaction＇　is　proposed.　Compared　with　＇instant　liquefaction＇　in　conventional　test,　it　is　found　that　the　factors　affecting　the　dilatancy　of　saturated　sand　in　conventional　test　such　as　consolidation　stress　ratio,　density　and　particle　size　would　not　influence　the　occurrence　of　＇continued　liquefaction＇　in　cyclic　loading　test　under　confined　condition.