Masonry　buildings　are　primarily　constructed　out　of　bricks　and　mortar　which　become　discrete　pieces　and　cannot　sustain　horizontal　forces　created　by　a　strong　earthquake.　The　collapse　of　masonry　walls　may　cause　significant　human　casualties　and　economic　losses.　To　maintain　their　integrity,　several　methods　have　been　developed　to　retrofit　existing　masonry　buildings,　such　as　the　constructional　RC　frame　which　has　been　extensively　used　in　China.　In　this　study,　a　new　method　using　precast　steel　reinforced　concrete　(PSRC)　panels　is　developed.　To　demonstrate　its　effectiveness,　numerical　studies　are　conducted　to　investigate　and　compare　the　collapse　behavior　of　a　structure　without　retrofitting,　retrofitted　with　a　constructional　RC　frame,　and　retrofitted　with　external　PSRC　walls　(PSRCW).　Sophisticated　finite　element　models　(FEM)　were　developed　and　nonlinear　time　history　analyses　were　carried　out.　The　results　show　that　the　existing　masonry　building　is　severely　damaged　under　occasional　earthquakes,　and　totally　collapsed　under　rare　earthquakes.　Both　retrofitting　techniques　improve　the　seismic　performance　of　existing　masonry　buildings.　However,　it　is　found　that　several　occasional　earthquakes　caused　collapse　or　partial　collapse　of　the　building　retrofitted　with　the　constructional　RC　frame,　while　the　one　retrofitted　by　the　proposed　PSRC　wall　system　survives　even　under　rare　earthquakes.　The　effectiveness　of　the　proposed　retrofitting　method　on　existing　masonry　buildings　is　thus　fully　demonstrated.　©　2021,　Institute　of　Engineering　Mechanics,　China　Earthquake　Administration.