Protein-protein　docking　is　usually　exploited　with　a　two-step　strategy,　i.e.,　conformational　sampling　and　decoy　scoring.　In　this　work,　a　new　filter　enhanced　sampling　scheme　was　proposed　and　added　into　the　RosettaDock　algorithm　to　improve　the　conformational　sampling　efficiency.　The　filter　term　is　based　on　the　statistical　result　that　backbone　hydrogen　bonds　in　the　native　protein　structures　are　wrapped　by　more　than　nine　hydrophobic　groups　to　shield　them　from　attacks　of　water　molecules　(Fernandez　and　Scheraga,　Proc　Natl　Acad　Sci　USA　2003;100:113-118).　A　combinatorial　scoring　function,　ComScore,　specially　designed　for　the　other-type　protein-protein　complexes　was　also　adopted　to　select　the　near　native　docked　modes.　ComScore　was　composed　of　the　atomic　contact　energy,　van　der　Waals,　and　electrostatic　interaction　energies,　and　the　weight　of　each　item　was　fit　through　the　multiple　linear　regression　approach.　To　analyze　our　docking　results,　the　filter　enhanced　sampling　scheme　was　applied　to　targets　T12,　T20,　and　T21　after　the　CAPRI　blind　test,　and　improvements　were　obtained.　The　ligand　least　root　mean　square　deviations　(L_rmsds)　were　reduced　and　the　hit　numbers　were　increased.　ComScore　was　used　in　the　scoring　test　for　CAPRI　rounds　9-12　with　good　success　in　rounds　9　and　11.