The traditional single-channel discrete UART transceiver has low integration and poor reliability, which cannot meet the needs of modern flight control computers to interconnect with a large number of external devices. In this paper, a highly integrated fault-tolerant RS-422 transceiver system is proposed, which adopts the standby redundancy architecture, designs the channel fault logic, bus output enable control, and wrap-around monitor to determine channel validity and perform channel switching, and at the same time, designs the BIT method to improve the reliability and testability, furthermore uses the FPGA coding instead of discrete devices to improve the integration. The results show that the system has high reliability and testability, while the highly integrated design reduces the PCB area by 83.45%, and the maximum delay of the system is 5.485 ns. The system has a significant advantage over the traditional discrete devices.