Be aimed at the problem of analogy carried telephone which used in production process has large real-time calling noise, effecting managing effect, suggests that motor vehicles-line communication system based on spread spectrum famous as anti-interference. It uses ARM and spread spectrum together and gives hardware of pronunciation communication module, extended memory of main control module, spread spectrum treating module, CPLD module and so on. The design of software uses object-oriented Programming. Practice shows that the system reaches the high real-time requirements while achieving high clarity.