Abstract: In order to achieve precise synchronization among multi-module redundancy embedded electronic system of aerospace，this paper deals with the time synchronizing algorithm of the hot redundancy systems based on IEEE1588 protocol and FPGA（field programmable gate array）/ASIC(application specific integrated circuit), which combines the software with the hardware. This method can achieve the same precision as the hardware synchronizing and owns the fault-tolerant ability. The time synchronization precision of this algorithm is at hundreds of nanoseconds, and the algorithm is validated by system simulation.

Key words: time synchronization, IEEE1588, multi-module redundancy, embedded electronic system