The invention provides a voice transmission system and method. The system comprises a sending end, a receiving end, a gateway switch and a VPN. The sending end and the receiving end establish communication connection through the gateway switch and the VPN, and information interaction between the two platform ends is achieved through the gateway switch and the VPN. The method comprises the following steps: s1, the voice data are requested and processed to obtain voice data with a voice vlan tag; s2, the sending end sends verification data and receives returned verification data after multi-stage processing; s3, the voice data and the verification data are recombined, deleted and output. According to the invention, the VPN participates in the verification stage through regional coding, and the processing of verification data is distributed to each stage of the whole information interaction, so that the pressure of the sending end and the receiving end is reduced, the data security risk is reduced, the overall transmission efficiency is improved, and the effectiveness and security of data transmission are ensured.