In　this　study,　a　modified-sawdust　lubricant　oil　filter　(MSF)　was　developed　and　its　effect　on　emission　characteristic　and　performance　of　diesel　engine　was　studied　compared　with　conventional　fiber-paper　oil　filter　(CPF).　The　tests　were　performed　using　a　six-cylinder,　heavy-duty　direct　injection　diesel　engine.　In　steady　state,　the　brake-specific　fuel　consumption　(BSFC),　engine　output　power　and　engine　oil　pressure　were　measured　at　nine　different　typical　engine　speeds.　Exhaust　emissions　of　nitrogen　oxides　(NOx),　particulate　matter　(PM),　carbon　monoxide　(CO)　and　hydrocarbons　(HC)　were　analyzed　according　to　European　Steady-state　Cycle　(ESC).　Besides,　lubricant　oil　samples　were　extracted　from　the　crankcase　in　the　equipment　of　MSF　and　CPF　individually.　Then　the　kinematic　viscosity,　colloids　and　metal　content　of　oil　samples　were　determined.　The　results　showed　that　MSF　effectively　reduced　wear　metal　accumulation　and　insoluble　colloids　in　lubricating　oil,　and　thus　retarded　deterioration　of　oil　viscosity.　Compared　with　CPF,　an　increase　of　2.7　kW　in　maximum　output　power　and　decrease　of　1.66–2.85%　in　BSFC　were　observed　for　MSF.　In　addition,　the　using　of　MSF　significantly　reduced　HC　(60.9%)　and　PM　(12.5%)　emission　while　increased　CO　and　NOx　emission　slightly.　The　results　proved　that　MSF　is　a　suitable　choice　for　diesel　engine　to　improve　engine　performance　and　reduce　exhaust　emissions.　©　2018　Elsevier　Ltd