System design of a bus bridge for 1553B and RS485 bus is proposed here to realize the communication between 1553B bus and RS485 bus.Hardware design of the bus bridge is introduced.The regular time characteristic of 1553B protocol is used in the logic design in FPGA.The high reliability methods adopted in the bridge system are described also.DDCs 1553B test card and a board with 1553B protocol over RS485 transceivers are used to test the bus bridge design

and the bit error rate is less than 10.The experimental results prove the validity and reliability of the bridge design.Design of the bus bridge is real-time and easy to implement over FPGA

and take up little hardware resources.