To　provide　an　effective　basis　and　reference　for　applications　of　prestressed　concrete　thin-slab　beams　after　a　bridge　fire,　methods　and　principles　of　fire-resistant　design,　repair,　and　reinforcement　of　such　beams　were　discussed.　Taking　a　simple　supported　and　continuous　girder　bridge　of　an　expressway　in　service　as　a　sample,　appearance　testing　and　nondestructive　testing　of　the　internal　structure　were　carried　out.　Four　representative　full-scale　prestressed　concrete　beams　were　selected.　Through　the　comparative　test　of　the　ultimate　bearing　capacity　of　such　beams,　the　laws　of　the　deflection　deformation,　strain　distribution,　crack　formation,　and　crack　development　were　obtained.　By　combining　with　the　finite　element　simulation　and　theoretical　analysis,　the　ultimate　bearing　capacity,　complex　mechanical　characteristics,　and　breakage　feature　and　failure　mechanism　of　such　beams　were　studied.　It　was　indicated　by　the　results　the　following:　(1)　Prestress　loss　will　cause　height　reduction　of　the　concrete　shear　zone,　which　is　one　of　the　main　reasons　why　the　bending-shearing　failure　of　such　beams　happened　before　the　pure　bending　failure.　(2)　Under　certain　operating　loads,　brittle　fracture　is　more　likely　to　occur　on　the　bottom　surface　of　such　beams　when　directly　exposed　to　fire.　(3)　The　bursting　and　spilling　depth　of　concrete　after　being　exposed　to　fire　can　be　used　as　the　characteristic　parameters　for　the　rapid　identification　of　the　bottom　surface　of　such　after-fire　beams.