Monitoring　the　dynamic　responses　of　bridge　structures　has　received　considerable　attention.　It　is　important　to　synchronously　measure　both　the　quasi-static　and　dynamic　displacements　of　bridge　structures.　However,　the　traditional　accelerometer　method　cannot　capture　the　quasi-static　displacement　component,　although　it　can　detect　the　dynamic　displacement　component.　To　this　end,　a　novel　composite　instrument　of　a　smartstation　was　proposed　to　monitor　vibration　displacements　of　footbridges.　Full-scale　experiments　were　conducted　on　a　footbridge　to　validate　the　feasibility　of　the　composite　instrument-based　monitoring　method.　A　Chebyshev　filter　and　wavelet　algorithms　were　developed　to　process　the　composite　instrument　measurements.　It　was　concluded　that　the　measurement　noise　of　the　composite　instrument　was　mainly　distributed　in　a　frequency　range　of　0-0.1　Hz.　In　two　case　studies　with　displacement　peaks　of　5.7-10.0　mm　and　1.3-　2.5　mm,　the　composite　instrument　accurately　identified　the　quasi-static　and　dynamic　displacements.　The　composite　instrument　will　be　a　potential　tool　for　monitoring　structural　dynamics　because　of　its　enhanced　overall　performance.　©　2020　by　the　authors.