As　a　dynamic　non-destructive　technique,　Acoustic　Emission　has　the　capability　to　detect　the　leakage　of　the　pipeline　in　time.　The　traditional　cross　correlation　technique　does　not　perform　well　for　acoustic　leak　location.　The　Modal　Acoustic　Emission　suggests　that　the　acoustic　emission　signal　is　actually　guided　wave　and　has　the　characteristics　of　multi-mode　and　dispersion.　Based　on　the　theory　of　the　Modal　Acoustic　Emission,　isolating　the　mode　from　the　leak　signals　will　be　of　help　to　obtain　the　exact　information　of　the　source　and　improve　the　accuracy　of　leak　location.　Therefore　selection　of　appropriate　mode　is　the　key　to　improve　the　accuracy　of　leak　location.　A　phase　spectrum　method　was　used　to　extract　the　dominant　mode＇s　phase　velocities　from　the　experiment　data　at　a　range　of　frequency.　Experiments　had　been　conducted　on　different　outside　diameter　pipes　to　verify　the　dispersion　predictions　and　the　dominant　mode　propagated　at　different　distance.　While　compared　to　the　predicted　mode　phase　velocity　curves,　it　was　showed　that　the　dominant　mode　received　by　sensors　was　the　dispersive　F(1,1)　mode　over　short　path　lengths.　The　research　can　provide　guideline　for　mode　selection　of　leak　location　and　can　help　to　improve　the　accuracy　of　leak　location.