Abstract: A new fault-tolerant method by ISP partial reconstruction is proposed,which can obviously reduce the reconfiguration data.The principle,arithmetic and characteristics of the new fault-tolerant method are described.In order to remove obstacle in the implement of the new fault-tolerant method,a new de-coupling circuit design method is presented.The new fault-tolerant method was employed in the telecommand data processing circuit for deep space exploration,and the implement process was demonstrated through Flash FPGA.