The selfrepairing feature of evolution hardware can effectively recover repairable faults of circuit systems. Due to the slow rate and low success rate in circuit evolution process, how to accomplish the evolution within the time constraint becomes a major challenge. We propose a realtime faulttolerant system based on evolution hardware, in which fault analysis trees are used to monitor circuit faults in real time，a fault compensation mechanism to maintain the normal operation of the system, and the evolution hardware technique is adopted to repair circuit faults so as to realize online realtime repair of faults. We test the faulttolerant system on FPGA through random fault injection. Several evolutionary algorithms are used to verify the selfrepairing capability of the faulttolerant system. The results show that the repair rate of the fault circuit can reach 95% under the realtime constraint and the stability and reliability of the system are improved.