Model-based　control　methods　have　been　acknowledged　as　powerful　solutions　for　hydraulic　manipulators　through　compensating　nonlinear　dynamics.　Hydraulic　oil,　as　the　working　medium　for　energy　transfer,　significantly　affects　the　system＇s　rigidity　and　control　performance.　In　most　studies,　the　effective　bulk　modulus　of　oil　is　either　treated　as　a　constant　or　estimated　as　an　unknown　parameter.　However,　it　is　closely　related　to　working　pressure　and　can　vary　several　times　under　different　pressures.　Although　several　theoretical　models　for　the　effective　bulk　modulus　exist,　their　complexity　and　dependence　on　specific　measurement　equipment　limit　models＇　application　in　hydraulic　manipulator　control.　In　this　study,　a　control-oriented　model　for　the　effective　bulk　modulus　is　developed,　balancing　the　feasibility　of　control　design　and　the　accuracy　of　the　model　description.　A　model-based　controller　is　then　synthesized　for　a　multi-degree-of-freedom　hydraulic　manipulator.　Through　an　especially　designed　X-swapping　scheme,　the　primary　parameters　of　the　manipulator,　including　those　in　the　bulk　modulus　model,　can　be　updated　online　without　additional　hardware　dependencies.　Theoretical　analysis　and　experiment　results　demonstrate　that　the　method　improves　the　dynamic　performance　of　hydraulic　manipulators　under　varying　pressures.　Notably,　this　represents　the　first　instance　where　a　hydraulic　manipulator　controller　accounts　for　the　nonlinear　characteristics　of　the　effective　bulk　modulus.