An　efficient　H.264　bit　rate　transcoding　scheme　based　on　PID　controller,　is　proposed　in　this　paper.　In　the　scheme,　simplified　cascaded　pixel　domain　transcoding　structure　is　adopted　to　reduce　the　computational　complexity　while　remaining　the　comparable　reconstructed　video　quality.　Furthermore,　a　PID　controller　is　introduced　in　the　frame　layer　to　ensure　the　output　bit　rate　consistent　with　the　target　bit　rate.　The　experimental　results　show　that,　the　scheme　proposed　in　the　paper　can　achieve　high　bit　rate　accuracy,　which　is　an　efficient　bit　rate　transcoding　scheme.