Public　transport　(PT)　competitiveness　refers　to　the　advantage　and　attraction　of　PT　compared　to　other　modes　of　transport　from　a　specific　perspective.　In　recent　years,　research　on　PT　competitiveness　based　on　accessibility　has　made　significant　progress,　but　the　research　on　impact　mechanisms　of　external　influencing　factors　on　PT　competitiveness　is　lagging　behind.　This　study　addressed　this　gap　by　using　a　Space　Barrier　model　(SBM)　to　evaluate　PT　competitiveness　relative　to　private　cars　based　on　real　traffic　data　from　Beijing.　Additionally,　a　Spatial　Durbin　model　(SDM)　was　used　to　analyze　the　spatiotemporal　relationship　between　PT　competitiveness　and　six　built　environment　(BE)　variables,　including　the　detour　coefficient　of　PT,　bus　stop　density,　land　use　mixture,　metro　station　density,　residential　density,　and　road　network　density　during　peak　and　off　-peak　hours.　This　study　has　identified　that　the　influence　of　BE　variables　varies　across　different　time　periods.　Specifically,　land　use　mixture　demonstrates　notably　stronger　effects　during　peak　hours　as　opposed　to　off　-peak　hours.　During　evening　peak　hours,　the　influence　of　land　use　mixture　on　PT　competitiveness　at　the　origin　location　(CO)　is　27.4%　higher　than　the　effect　during　off　-peak　hours.　Moreover,　this　investigation　has　uncovered　the　spatial　dependence　characterizing　the　relationship　between　each　BE　and　PT　competitiveness.　It　has　indicated　that　BE　exert　both　direct　and　indirect　impacts　on　PT　competitiveness.　For　instance,　metro　station　density　extends　the　PT　competitiveness　within　both　the　area　it　is　located　and　its　surrounding　areas.　During　the　evening　peak　hours,　when　metro　density　increases　by　1%,　the　CO　in　the　area　it　is　located　and　in　its　surrounding　areas　will　respectively　decrease　0.045%,　and　0.143%.　Overall,　this　research　offers　valuable　insights　for　bus　transit　operators　and　policymakers　seeking　to　enhance　PT　efficiency　and　competitiveness　by　devising　strategies　such　as　skipping　stops　during　off　-peak　hours,　balancing　regional　PT　facility　supply,　optimizing　the　connectivity　of　PT,　and　increasing　the　density　of　PT　stations.