Abstract: A design method based on evolvable hardware is proposed for N-modular redundancy fault-tolerant system with different structures.Firstly,a multi-objective genetic algorithm is improved and is used to design some target digital circuits of multi-modular redundant system.Secondly,an evaluation strategy of multi-modular digital circuits with different structures is presented to optimize the design of N-modular system with different structures.Finally,the designed digital circuits with different structures are used to form the N-modular redundancy fault-tolerant system so as to enhance the reliability of the fault-tolerant system.The fault-tolerant capability of target circuits evolved by single-objective and multi- objective genetic algorithms and that of the systems composed of digital circuits with the same and different structures are analyzed theoretically and compared.An evaluation method and a selection strategy are designed for digital circuits with different structures.Experiments are made with 8-3 coder as an example,and the experimental results prove that the fault-tolerant system composed of circuits with different structures evolved by multi-objective genetic algorithm can obtain better fault-tolerant capability.