This　paper　proposed　a　whole　new　design　for　RV40(realvideo40)　video　decoder　from　FFmpeg(fast　forward　Moving　Picture　Experts　Group),which　is　in　lack　of　the　ability　to　decode　smoothly　when　decoding　a　period　of　high　bit　rate　frames　within　some　video　streams.　The　design　specially　optimized　the　sub　pixel　interpolation　algorithm,　which　is　the　core　of　motion　compensation.　The　design　uses　detailed,　different　algorithms　based　on　different　frame　types.　Meanwhile　a　temporal　related,　flexible　algorithm　usage　method　is　introduced　to　deal　with　the　jamming　in　decoding　sequence.　The　time　consumed　by　calculating　is　reduced　with　an　acceptable　reduced　frame　appearance.　This　design　is　used　on　a　test　platform　for　testify.　The　result　returned　shows　that　this　design　can　greatly　promote　decoding　performance　up　to　50%　while　reducing　a　little　picture　performance.　©2010　IEEE.