In　the　shaking　table　test　of　a　soil-pile-bridge　structure　system,　it　is　difficult　to　keep　the　similarity　relations　of　the　model　structure　and　that　of　the　model　soil　consistent.　Due　to　the　difference　of　geometry　and　material　similarity　ratios　for　the　model　structure　and　model　soil,　the　determination　of　the　duration　compression　ratio　of　input　motions　is　a　key　problem.　The　spectrum　characteristics　of　input　motions　will　be　varied　by　the　duration　compression　ratio　so　that　the　seismic　responses　of　structure　and　soil　system　will　be　affected.　There　are　three　commonly　used　approaches　to　determine　the　duration　compression　ratio　of　input　motions　in　shaking　table　tests:　the　time　similarity　ratio　of　model　structure;　the　time　similarity　ratio　of　model　soil;　and　uncompressed.　To　study　the　influence　of　the　duration　compression　ratio　on　the　seismic　response　of　a　soil-structure　system　in　shaking　table　tests,　the　El　Centro　record　and　the　Wolong　record　were　chosen　as　the　input　motions,　and　the　durations　were　compressed　by　the　three　commonly　used　approaches　in　this　paper.　The　influence　of　the　duration　compression　ratios　of　the　input　motions　on　the　acceleration　response　of　a　soil-pile-bridge　structure　system　was　compared　and　analyzed　through　a　series　of　shaking　table　tests.　The　results　showed　that　the　duration　compression　ratio　affected　the　acceleration　response　of　the　model　soil　and　the　model　structure,　and　the　effect　was　more　obvious　when　the　peak　ground　acceleration　(PGA)　was　small.　If　the　research　is　focused　on　the　seismic　response　of　the　soil,　it　is　recommended　to　use　the　time　similarity　ratio　of　the　model　soil　to　compress　the　input　motions.　If　the　research　is　focused　on　the　seismic　response　of　the　structure,　it　is　recommended　to　use　the　time　similarity　ratio　of　the　model　structure　to　compress　the　input　motions.　This　study　could　provide　a　reference　for　the　design　of　the　shaking　table　test　of　a　soil-pile-bridge　structure　system.