Abstract: On the basis of queuing theory,the paper built a mathematical model for CAN bus protocol, analyzed characteristics of hybrid transmission of data and voice in communication system with Matlab simulation platform and expounded relationship between system load and average transmission time delay of every frame. A hardware communication system with microprocessor PIC18F258, voice processing module AMBE-2000 and A/D-D/A chip PCM3500 was built and corresponding experiment test was made, which realized hybrid transmission of data and voice.