Based　on　the　International　Telecommunication　Union　Telecommunication　Standardization　Sector　(ITU-T)　recommendation　for　EV-VBR　coding　standard　and　the　candidate　codec　designed　by　Speech　and　Audio　Signal　Processing　Laboratory　(SASPL)　of　Beijing　University　of　Technology,　an　improved　embedded　variable　bit　rates　wideband　speech　codec　was　proposed.　In　the　improved　codec,　ACELP　coding　was　implied　to　the　first　two　coding　layers.　The　middle　sub-frame　spectral　parameters　were　computed　and　quantized.　Three　pulses　depth　first　tree　search　algorithm　was　designed.　On　the　higher　three　coding　layers　embedded　TCX　coding　was　reconstructed　by　accumulating　frequency　coefficients　vectors.　Additionally,　VAD　and　DTX　functions　were　implemented　in　the　improved　codec.　Test　results　show　that　the　improved　codec　achieves　better　speech　quality　and　much　lower　coding　complexity　than　the　original　codec.　The　speech　quality　and　coding　efficiency　are　comparable　with　G.718　of　a　new　ITU-T　speech　coding　standard　and　the　low　delay　feature　is　retained.