A novel speech codec of high quality and low complexity——PS ACELP (pre search algebraic code excited linear prediction) is presented in this paper, which is suitable for software based compressing and replaying speech on H/PC. The proposed codec is almost equal in speech quality with ITU T G.723.1 5.3kbps codec, but one third of the complexity of the latter, only around 7 MIPS. How to achieve the low computing complexity is described in detail in this paper. Due to the advantages of high speech quality, low complexity and low bit rate, PSACELP codec is suitable for software based compressing and replaying of speech, voice mail and Internet phone etc.