In　recent　years,　with　the　mature　of　linear　motor　technology,　linear　motor　has　been　more　and　more　widely　applied　in　the　field　of　hydraulics.　The　water　hydraulic　reciprocating　piston　pump　driven　by　linear　motor　has　the　advantages　of　constant　flow　and　low　vibration.　Compared　with　traditional　piston　pump　which　can　only　regulate　the　movement　of　the　pump　by　means　of　rotor　speed　control,　the　water　hydraulic　pump　can　get　a　good　flow　output　performance　through　servo　control.　For　the　large　flow　bilge　pump　used　in　naval　ships,　this　paper　use　a　novel　four　double-action　linear　motors　to　drive　eight　pistons.　In　this　research,　the　system　simulation　model　is　established,　and　the　static　stress　analysis　and　modal　analysis　are　conducted.　As　a　result,　we　obtain　ten　orders　natural　frequency　and　amplitude　of　the　system,　and　then　discuss　the　different　position　of　vibration　situation　when　a　damping　module　is　added　in　the　system.　The　lowest　frequency　of　the　system　is　close　to　1507　Hz,　which　is　much　large　than　the　motion　frequency.　And　with　added　the　damping　module,　the　lowest　maximum　deformation　is　reduced　to　4　mm　and　occurs　on　cylinder　joint.　The　research　work　provides　an　effective　method　to　analyze　the　vibration　of　the　water　hydraulic　reciprocating　piston　pump　driven　by　linear　motor.　It　is　suitable　for　further　dynamic　analysis　and　structure　optimum　design　to　reduce　the　vibration　of　the　water　hydraulic　piston　pump.