H.264/AVC　adopts　intra　coding　technique　to　reduce　spatial　redundancies.　In　order　to　achieve　better　coding　performance,　there　are　nine　candidate　modes　for　4x4　block　unit　to　be　selected　by　Rate-Distortion　Optimization(RDO)　process　in　the　H.264/AVC　encoder-side.　However,　too　many　intra　candidate　modes　undoubtedly　increase　the　transmitted　bits　that　represent　them.　To　solve　this　problem,　a　novel　method　for　reducing　the　number　of　intra　modes　is　proposed　in　this　paper.　For　each　4　x　4　block,　our　algorithm　can　cluster　the　nine　candidate　modes　into　several　groups　and　selects　one　mode　from　each　group　as　a　representative　of　all　the　modes　in　this　group,　so　the　cost　of　transmission　can　be　reduced　significantly　because　of　the　reduction　of　number　of　candidate　modes.　Experimental　results　show　that　the　proposed　method　achieves　3.2%　bit-rate　reduction　on　average　for　various　video　sequences.　The　improvement　of　coding　performance　can　be　up　to　7%　bit-rate　reduction　at　low　bit　rate,　averagely.　©　2011　IEEE.