Due　to　the　multiple　modes　and　dispersive　nature　of　acoustic　leak　signal　propagation　in　pipeline,　the　traditional　AE　cross　correlation　method　was　ineffective　to　location　the　leak　in　pipeline.　Based　on　the　theory　of　modal　acoustic　emission　(MAE),　two　different　pipeline　leak　location　techniques　are　brought　forward.　One　is　based　on　two　modes　with　one　sensor;　the　other　is　based　on　one　mode　with　two　sensors.　The　general　process　is　narrated　as　following　three　steps.　Firstly,　based　on　the　theory　of　guided　waves　propagation　in　cylinder,　the　acoustic　leak　signals　in　positions　nearby　the　sensor(s)　can　be　predicted　using　the　information　of　dispersion　characteristics　of　guided　waves　in　pipeline　and　the　acoustic　signal　received　by　the　sensor(s).　Secondly,　by　transformed　the　predicted　signals　in　time　and　space,　two　(one)　individual　modes　(mode)　of　the　acoustic　signal　at　the　position　of　the　sensor(s)　are　isolated.　By　correlated　the　two　modes　of　the　same　sensor　(one　mode　of　the　two　sensors),　the　leak　position　can　be　located　accurately.　The　leak　location　experiments　have　been　carried　out　to　prove　the　validity　of　the　one　sensor　and　two　sensors　leak　location　techniques;　it　is　indicated　that　the　location　errors　of　the　two　leak　location　techniques　are　usually　less　than　5,　and　the　techniques　can　be　used　to　location　the　leak　of　pipeline　filled　with　liquid　or　gas.　Copyright　©　2004　by　ASME.