MELP (Mixed Excitation Linear Prediction) vocoder is widely used in commercial and military speech communication because of its low-bit-rate, low-delay and low-complexity. This paper at first surveys the development and the current progress of the speech coding, the principle and performance of MELP vocoder. The hardware and software implementation of 2.4kbit/s MELP vocoder on TMS320C6713 DSP are introduced, including the speech input and output circuit, program transplanting and optimization, and flash burn. Comparing the speech qualities of the coded and un-coded,this paper gives out the results of the experiment and the conclusion. Informal subjective listening tests show that the speech quality of 1.2kb/s coding algorithm achieves high intelligibility, clearness, and relative naturalness.