The　quality　of　underwater　bridge　piers　significantly　impacts　bridge　safety　and　long-term　usability.　To　address　limitations　in　conventional　inspection　methods,　this　paper　presents　a　sonar-based　technique　for　the　three-dimensional　(3D)　reconstruction　and　visualization　of　underwater　bridge　piers.　Advanced　MS1000　scanning　sonar　is　employed　to　detect　and　image　bridge　piers.　Automated　image　preprocessing,　including　filtering,　denoising,　binarization,　filling,　and　morphological　operations,　introduces　an　enhanced　wavelet　denoising　method　to　accurately　extract　the　foundation　contour　coordinates　of　bridge　piers　from　sonar　images.　Using　these　coordinates,　along　with　undamaged　pier　dimensions　and　sonar　distances,　a　model-driven　approach　for　a　3D　pier　reconstruction　algorithm　is　developed.　This　algorithm　leverages　multiple　sonar　data　points　to　reconstruct　damaged　piers　through　multiplication.　The　Visualization　Toolkit　(VTK)　and　surface　contour　methodology　are　utilized　for　3D　visualization,　enabling　interactive　manipulation　for　enhanced　observation　and　analysis.　Experimental　results　indicate　a　relative　error　of　13.56%　for　the　hole　volume　and　10.65%　for　the　spalling　volume,　demonstrating　accurate　replication　of　bridge　pier　defect　volumes　by　the　reconstructed　models.　Experimental　validation　confirms　the　method＇s　accuracy　and　effectiveness　in　reconstructing　underwater　bridge　piers　in　three　dimensions,　providing　robust　support　for　safety　assessments　and　contributing　significantly　to　bridge　stability　and　long-term　safety　assurance.