How to use Multi-SerialPorts to communicate in the VxWorks real-time operating systems is introduced. The hardware’s setting options are described. The design points such as initialization of SEM/MSP-8 at the application-layer, the setting of the base address and the connecting interrupt are emphasized. Data sending function and interrupt receiving function are implemented successfully in the multi-serial ports working modes including RS232/RS422. In order to get one-to-several communication, the broadcast in the RS485 mode is adapted to different address. For the purpose of improving stability of transferring, a method of analyzing single data frame of transferring protocol in the single character equipment is put forward. At last, it points out how and why to use watchdog at VxWorks for timing.