Water　hammer　pressure　pulsation　is　caused　by　the　switching　characteristics　of　digital　hydraulics,　resulting　in　a　decline　in　digital　hydraulic　performance,　which　is　also　a　research　difficulty　of　digital　hydraulics.　However,　the　current　classical　water　hammer　theory　cannot　accurately　describe　the　water　hammer　pressure　pulsation　in　the　digital　hydraulic　system.　Therefore,　the　water　hammer　pressure　pulsation　of　digital　hydraulic　system　is　described　by　experimental　method.　Three　phenomena　were　found　by　using　the　designed　water　hammer　pressure　pulsation　test　bench:　(1)　In　the　process　of　propagation,　the　waveform　of　water　hammer　pressure　fluctuation　has　three　kinds　of　changes　with　the　increase　of　driving　frequency.　(2)　When　the　switching　frequency　of　the　high-speed　on-off　valve　is　not　less　than　130　Hz,　the　stability　time　of　the　water　hammer　pressure　pulsation　is　proportional　to　the　switching　frequency.　(3)　After　the　water　hammer　pressure　fluctuation　is　stable,　the　water　hammer　pressure　fluctuation　will　increase　first　and　then　decrease　with　the　increase　of　frequency.　©　2023　IEEE.