Ultrasonic　guided　wave　(UGW)　technique　has　been　widely　utilized　in　damage　detection　of　pre-stressed　steel　strands.　However,　most　of　the　current　UGW-based　methods　only　focus　on　bare　strands,　whereas　in　real　projects　the　strands　are　usually　pre-buried　inside　the　structure　and　encapsulated　by　media　such　as　concrete　or　grout.　In　this　study,　the　effects　of　various　grouting　and　tensioning　factors　on　the　propagation　of　UGW　in　grouted　steel　strand,　as　well　as　the　effectiveness　of　UGW　energy　leakage　ratio　(alpha　EL)-based　pre-stress　evaluation　for　grouted　steel　strand,　were　investigated.　Firstly,　the　theoretical　model　of　UGW　propagating　in　the　grouted　steel　strand　was　developed.　Secondly,　a　finite　element　model　of　grouted　strand　was　established　to　investigate　the　dispersion　characteristic　of　UGW　as　well　as　the　energy　distribution　and　attenuation　behavior　of　UGW　in　the　grout.　Thirdly,　pre-stressed　concrete　(PSC)　specimens　with　different　grouting　diameters,　grouting　lengths,　and　tension　forces　were　designed　to　investigate　the　effects　of　grouting　thickness,　grouting　length,　and　tension　force　on　the　group　velocity,　energy　distribution　and　alpha　EL　of　UGW.　Finally,　the　alpha　EL-based　approach　was　validated　in　pre-stress　evaluation　for　grouted　steel　strand,　and　the　evaluation　accuracy　was　compared　with　that　for　bare　steel　strand.　Results　show　that　compared　with　the　helical　wire　excitation　scenario,　the　UGW　signals　propagating　in　steel　strands　are　significantly　less　affected　by　variations　in　grouting　thickness　and　grouting　length　under　core　wire　excitation　scenario.　In　the　grout,　the　UGW　energy　tends　to　decrease　exponentially　with　the　increase　of　the　radial　propagation　distance,　and　the　helical　wire　excitation　scenario　leads　to　more　UGW　energy　leaking　into　the　grout　compared　with　core　wire　excitation.　It　is　recommended　to　excite　UGW　signal　in　the　core　wire　instead　of　the　helical　wire　in　alpha　EL-based　pre-stress　evaluation　approach　for　grouted　steel　strand,　in　such　scenario,　the　evaluation　error　is　only　4.93　%.