The　boride　layer　was　prepared　on　the　surface　of　Ti–5Al–2.5Sn　alloy　by　powder-pack　borided　at　975–1075　°C　for　20　h　with　a　temperature　interval　of　25　°C,　and　surface　morphology,　phase　composition,　microstructure,　hardness,　and　wear　properties　of　the　borided　Ti–5Al–2.5Sn　alloy　were　investigated.　The　crystal　parameters　of　TiB2　phase　in　the　boride　layer　at　different　boriding　conditions　were　obtained　from　the　Rietveld　structure　refinement　of　Ti–5Al–2.5Sn　samples,　and　the　theoretical　hardness　values　of　TiB2　were　calculated　using　the　first-principles　calculations.　The　results　indicate　that　the　boride　layer　comprises　the　outer　TiB2　layer　and　the　inner　TiB　whisker,　and　TiB2　layer　thickens　and　TiB　whiskers　coarsen　with　the　increase　of　temperature.　The　hardness　of　TiB2　layer　is　related　to　the　boriding　temperature,　the　greater　hardness　of　TiB2　layer　corresponds　to　the　higher　boriding　temperature,　which　is　in　good　agreement　with　the　theoretically　predicted　results.　Ti–5Al–2.5Sn　alloy　borided　at　1075　°C–20　h　has　the　highest　hardness　and　excellent　wear　resistance.　Finally,　wear　mechanisms　were　also　discussed,　which　is　a　combination　of　abrasive　and　adhesive　wear.　©　2023　The　Author(s)