Based　on　the　non-navigable　span　continuous　girder　bridge　of　Hong　Kong-Zhuhai-Macau　Bridge,　the　effect　of　water-structure　interaction　on　dynamic　characteristics　of　the　bridge　is　studied.　Acoustic　fluid-structure　interaction　method　is　used　to　simulate　the　hydrodynamic　effect,　the　results　of　eigenvalue　analysis　and　frequency　response　functions　of　displacement　are　presented　under　six　cases　of　water　depths.　The　influence　of　water　depth　on　nature　vibration　frequency　and　amplitude　of　resonant　peak　is　studied.　The　results　show　that　as　water　depth　increasing,　the　natural　vibration　frequency　decreases　but　the　amplitude　of　resonant　peak　doesn＇t　keep　increasing.　Besides　influence　on　vibration　frequency　and　amplitude　are　both　more　obvious　to　higher　modes.