Water　tank　is　one　important　component　of　passive　containment　cooling　system　(PCS)　of　nuclear　island　building.　The　sloshing　frequency　of　water　is　much　less　than　structure　frequency　and　large-amplitude　sloshing　occurs　easily　when　subjected　to　seismic　loadings.　Therefore,　the　sloshing　dynamics　and　fluid-structure　interaction　(FSI)　effect　of　water　tank　should　be　considered　when　the　dynamic　response　of　nuclear　island　building　is　analyzed.　A　1/16　scaled　model　was　designed　and　the　shaking　table　test　was　done,　in　which　the　hydrodynamic　pressure　time　histories　and　attenuation　data　of　wave　height　were　recorded.　Then　the　sloshing　frequencies　and　1st　sloshing　damping　ratio　were　recognized.　Moreover,　modal　analysis　and　time　history　analysis　of　numerical　model　were　done　by　ADINA　software.　By　comparing　the　sloshing　frequencies　and　hydrodynamic　pressures,　it　is　proved　that　the　test　method　is　reasonable　and　the　formulation　of　potential-based　fluid　elements　(PBFE)　can　be　used　to　simulate　FSI　effect　of　nuclear　island　building.