Abstract: This paper presents a non-uniform and part-searching-area algebraic codebook based on Algebraic Code Excited Linear Preiction(ACELP) speech coding algorithm. The non-uniform algebraic codebook is determined by the non-uniform statistical properties of the algebraic codebook, and the part-searching-area is determined by the periodicity of the algebraic codebook excitation vector, which makes up the insufficient numbers of signed pulses in algebraic codebook at low bit rate. In order to preserve the continuity of pitch, different pitch detection methods are employed for speech/silence frame when these two techniques are used. Subjective and objective test results indicate that the reconstructed speech quality of 4kb/s DP-CELP speech coder is improved based on these techniques, especially for the female speakers.