A　characteristic　waveform　interpolation　(CWI)　speech　coding　algorithm　at　low　bit　rates　based　on　bi-orthogonal　lifting　wavelet　(BLWT)　is　proposed　in　this　paper.　The　complicated　characteristic　waveform　(CW)　alignment　operation　and　convolution　operation　of　filter　are　cancelled　by　using　BLWT-based　CW　decomposition.　The　memory　of　traditional　CW　wavelet　decomposition　algorithm　is　reduced　with　its　inherent　situ　calculation.　The　algorithm　delay　of　the　traditional　CW　decomposition　based　on　wavelet　transform　is　decreased　by　replacing　the　samples　of　adjacent　frames　with　the　boundary　samples　of　the　current　frame.　Each　decomposed　component　of　CW　is　independently　reconstructed　and　the　quantization　parameters　of　CW　are　flexibly　selected　according　to　the　human　ear＇s　perception.　Two　types　of　CWI　speech　codecs　at　1.84　kb/s　and　2.32　kb/s　are　designed　based　on　BLWT.　MOS　test　results　show　that　2.32　kb/s　BLWT-CWI　and　2.4　kb/s　MELP　have　similor　quality　and　the　performance　of　1.84　kb/s　BLWT-CWI　is　slightly　less　than　2.4　kb/s　MELP.　Subjective　A/B　listening　tests　also　show　that　the　quality　of　1.84　kb/s　BLWT-CWI　is　better　than　that　of　2　kb/s　LIWI(low　complex　improved　waveform　interpolation)codec.