It　is　difficult　to　separate　very　fine　particles,　say　of　the　order　of　microns,　from　water　with　conventional　hydrocyclones.　By　using　small　hydrocyclone　size　to　enhance　the　separation　capacity,　the　production　is　reduced.　This　paper　develops　a　novel　hydrocyclone　with　major　separation　in　a　small　cone-angle　area,　and　an　additional　large　cone-angle　area　is　introduced　to　connect　the　small　cone-angle　area　and　the　cylindrical　swirl　chamber　for　decreasing　pressure　drop　by　gradual　transition　of　fluids　from　entrance　to　separation　region.　Comprehensive　investigations　are　carried　out　on　the　pressure　drop　characteristics　of　this　novel　two-cone　hydrocyclone.　It　is　shown　by　experimental　results　that　production　of　this　novel　hydrocyclone　can　be　enhanced　by　60%~70%　in　comparison　with　conventional　single-cone　hydrocyclone.　Pressure　drop　increases　with　flow　rate　in　the　form　of　p∝q2,　but　decreases　with　the　diameter　of　overflow　orifice.　Large　split　ratio　(defined　as　the　ratio　of　the　flowrate　of　the　underflow　to　inlet　flow　rate)　significantly　gives　rise　to　high-pressure　drop.　When　the　length　of　vortex　finder　intrudes　into　the　swirl　chamber　increases,　the　pressure　drop　increases　at　first,　then　reaches　a　maximum　value,　and　later　decreases.