Switching　hydraulic　inertial　systems　(SIHS)　manipulate　the　interaction　of　inertial　and　capacitive　components　through　switching　valves　to　achieve　the　efficient　and　rapid　pressure　regulation.　However,　the　opening　and　closing　of　the　switching　valve　lead　to　fluid　expansion　and　compression　in　the　switched　volume,　which　generates　throttling　losses　in　the　switching　valve　transition　cycle,　resulting　in　substantial　energy　loss.　Hydraulic　soft　switching　is　an　essential　means　to　solve　the　loss　of　switching　valves.　However,　the　poor　resonance　performance　of　the　hydraulic　system　leads　to　arduousness　in　the　soft　switching　design.　Therefore,　this　paper　proposes　that　a　mechanical-hydraulic　coupling　mechanism　can　realize　the　soft　switching.　A　new　approach　is　proposed　to　realize　soft　switching　with　a　parallel　double-motor　mechanism　based　on　the　new　idea.　The　approach　connects　inertive　elements,　at　the　back,　to　the　switching　valve　to　suppress　the　sudden　flow　increase　caused　by　the　compressed　fluid　in　the　switched　volume　during　the　opening　transition　stage　of　the　switching　valve,　thus　effectively　reducing　the　loss　caused　by　the　throttling　flow　of　the　switching　valve.　The　new　approach　has　been　experimentally　verified　to　reduce　the　throttling　flow　by　33%,　resulting　in　an　increase　of　the　SIHS　output　efficiency　by　10%–15%.　©　2023　Elsevier　Ltd