For long-life products,the FPGA bitstream stored in NOR Flash may experience bit flips due to floating-gate charge leakage, which leads to FPGA configuration failure.To address this issue,this paper proposes a Flash refresh method based on FPGA multiboot.The Flash is refreshed during annual product maintenance to restore the floating-gate charge.The multiboot of the Kintex-7 series FPGA was investigated,and the configuration data composition was restructured to enhance the robustness of configuration.The optimized configuration data comprises one header file,two identical copies of the bitstream,and three identical sets of auxiliary file.When launching the Flash refresh,FPGA executes a sequential steps including self-check,data refresh,and read-back verification to ensure the reliability of the process.Test results have verified that this refresh method is stable and reliable,exhibiting high practical engineering utility.