In　order　to　achieve　the　high　compression　efficiency,　H.264/AVC　adopts　Rate-Distortion　Optimization　(RDO)　technology　with　full　mode　search　in　intra　prediction.　The　computational　complexity　is　so　high　that　it　isn＇t　fit　for　real　time　encoding　and　hardware　design.　So　we　proposed　a　fast　and　efficient　intra　prediction　algorithm.　We　choose　intra　luma　4x4　or　intra　luma　16x16　based　on　smooth　degree　of　region,　and　then　we　only　choose　part　modes　of　intra　luma　4x4,　intra　luma　16x16　and　intra　chroma　8x8　based　on　direction　gradient　of　pixels.　Experimentation　shows　that　our　algorithm　for　intra　prediction　can　save　more　than　75%　of　the　full　search　time　on　average　in　H.264　with　negligible　degradation　of　PSNR　and　increase　of　Bit-rate.