Using　molecular-dynamics　simulations　and　the　force-constant　model,　we　have　studied　the　Raman-active　tangential　modes　(TMs)　of　a　(10,0)　single-wall　carbon　nanotube　under　hydrostatic　pressure.　With　increasing　pressure,　the　atomic　motions　in　the　three　TMs　present　obvious　diversities.　The　pressure　derivative　of　E-1g,　A(1g),　and　E-2g　mode　frequencies　shows　an　increased　value　(d　omega(E1g)/dP＞0),　a　constant　value　(d　omega(A1g)/dP　similar　to　0),　and　a　negative　value　(d　omega(E2g)/dP　＜　0)　above　5.3　GPa,　respectively.　The　intrinsic　characteristics　of　TMs　consumedly　help　us　understand　the　essence　of　the　experimental　T　band　of　CNT.　The　anomalous　pressure　behavior　of　the　TM　frequencies　may　originate　from　the　tube　symmetry　alteration　from　D-10h　to　D-2h　then　to　C-2h.