Roots　blowers　are　widely　used　in　various　fields,　and　their　performances　are　extremely　important　for　their　application　in　the　chemical　industry.　In　this　study,　a　Roots　blower　with　a　flow　capacity　of　90　m(3)/min　was　investigated　using　a　computation　fluid　dynamics　(CFD)　approach,　with　emphasis　on　its　performance.　A　previous-generation　blower　comprising　two　lobes　was　simulated,　and　the　calculated　volumetric　efficiencies　were　compared　with　experimental　data.　After　validating　the　CFD　model,　the　performance　of　a　Roots　blower　with　two　to　six　lobes　was　predicted.　The　effect　of　the　sealing　angle　at　the　tip　of　the　profile　on　the　performance　of　the　blower　was　also　investigated.　An　optimized　profile　with　three　lobes　and　a　sealing　angle　of　4　degrees　was　selected.　A　new-generation　Roots　blower　with　the　same　capacity　as　that　of　the　previous-generation　was　manufactured　and　tested.　The　volumetric　efficiency　improvements　of　12.1%-18.2%　could　be　achieved　by　profile　optimization.