In　achieve　a　high　compression　ratio,　the　authors　proposed　order　to　a　DCT-based　energy　function,　which　is　used　to　estimate　the　textural　complexity　of　residual　blocks　of　intra　prediction.　Then　no　more　than　4　modes　instead　of　9　intra　prediction　modes　for　44　block　can　be　chosen　to　perform　RDO　according　to　the　textural　complexity　of　residual　block.　Consequently,　the　complexity　decreases　significantly.　Experiments　show　that　the　proposed　algorithm　can　save　about　48%　of　the　computation　time　stably　while　maintaining　the　PSNR-Bitrate　performance　of　H.264/AVC.