KTA　(Key　Technical　Area)　software　is　developed　from　the　H.264　reference　software　by　ITU-T　VCEG　to　establish　a　common　platform　for　developing　high　efficient　techniques　toward　next　generation　video　coding　standard.　With　new　techniques　integrated,　KTA　software　has　achieved　more　than　20%　improvement　over　H.264　in　average.　However,　these　new　techniques　not　only　bring　high　computations　but　also　require　multipass　encoding　optimization.　In　this　paper,　we　propose　two　methods　to　significantly　reduce　mode　checks　in　KTA　software.　First,　the　big　inter　mode　skipping　method　skips　modes　of　large　block　sizes　if　modes　of　smaller　block　sizes　are　better　in　an　preprocessing.　Second,　we　analyze　the　multi-pass　encoding　and　propose　the　fast　multi-pass　mode　decision　method,　which　only　checks　the　top　modes　in　the　first　pass　as　candidates　in　the　remaining　passes.　The　proposed　methods　have　reduced　the　encoding　time　as　much　as　80　percents　with　negligible　PSNR　loss　and　little　bit　rate　increase.　©2010　IEEE.