Contamination　control　in　fluid　power　system　is　a　challenge　due　to　the　fact　that　it　has　been　one　of　the　major　reasons　of　wear,　failure,　and　the　related　downtime.　A　novel　hydraulic　oil　purifier　proposed　in　this　study　is　considered　to　be　capable　of　removing　the　solid　particle　contaminant,　moisture,　and　gas　simultaneously,　which　consists　of　two　parts:　hydrocyclone　separator　and　rotating　packed　bed　(i.e.　Higee).　A　hydrocyclone　separator　used　to　be　applied　to　chemical　industry　is　tried　to　be　designed　according　to　experiential　parameters　in　a　typical　fluid　power　system　for　the　first　time.　And　then,　the　mathematical　model　of　the　hydrocyclone　separator　has　been　established.　The　distribution　of　the　hydraulic　oil　and　solid　particles　in　swirling　flow　field　inside　the　base　hydrocyclone　separator　has　been　simulated　with　the　help　of　computational　fluid　dynamics　software　Fluent.　The　effects　of　the　cone　angle　and　cylindrical　length　on　the　separation　performance　of　the　hydrocyclone　separator　have　been　subsequently　investigated.　Based　on　the　simulation　results,　the　hydrocyclone　separator　with　25　degrees　cone　angle　and　60mm　cylindrical　length　has　been　considered　as　the　most　satisfied　configuration.　Simulation　analysis　of　the　optimal　configuration　flow　field　reflects　a　relatively　pleasant　solid-liquid　separation　performance　considered　to　be　beneficial　to　controlling　the　contamination　level　of　fluid　power　system.　The　research　outcome　will　lay　a　foundation　for　the　development　of　the　new　hydraulic　oil　purifier　proposed　in　this　study.