The real-time operating system FreeRTOS is used to design a voice processing system based on Speex for voice recording and playback.The system uses the STM32F407 series single-chip microcomputer and audio processing chip WM8978 as the core.By transplanting the Speex algorithm, the voice technology such as codec and echo cancellation is adopted to realize the voice.It also proposes a circular buffer technology based on FreeRTOS queue and DMA interrupt for real-time processing of audio data.Through verification, the design can achieve better voice recording and playback, and encoding and decoding through the Speex algorithm can not only reduce memory requirements, but also effectively reduce noise.