This　study　developed　a　sonar　scanning　scheme　for　underwater　high-rise　pile　cap　foundations　(HRPCFs)　to　improve　the　efficiency　of　bridge　inspection　and　prolong　structural　durability.　First,　two　key　factors　in　the　measurement　point　arrangement　that　significantly　affect　the　accuracy　of　sonar　measurement-the　appropriate　range　of　measurement　distance　and　the　pitch　angle-were　determined　experimentally.　Subsequently,　an　assembled　platform　was　designed　to　firmly　hold　the　sonar　and　conveniently　move　it　under　strong　currents　to　effectively　provide　clear　images　of　the　pile.　A　strategy　was　developed　to　determine　the　appropriate　number　and　horizontal　and　vertical　positions　of　the　measurement　points　around　each　pile　in　the　pile　group,　particularly　to　avoid　the　obstruction　of　signal　propagation　caused　by　adjacent　piles　and　pile　caps.　The　method　was　applied　to　the　scanning　of　an　underwater　high-rise　pile　cap　foundation　of　a　bridge,　and　the　results　showed　that　the　scanning　ranges　of　the　imaging　sonar　at　all　arranged　measurement　points　were　not　affected　by　adjacent　piles.　The　imaging　sonar　carried　by　the　proposed　platform　could　obtain　clear　images　stably　at　a　water　speed　of　similar　to　2.0　m/s　and　obtain　all　surface　data　of　the　pile　quickly　and　completely.