Abstract: Based on 65 nm bulk CMOS technology, six kinds of DFFs including common DFF, DICE-DFF, FDICE-DFF, TMR-DFF, TTMR-DFF300 and TTMR-DFF600 were tested and analyzed by the shift register structure. Ti, Cu, Br, I, Au, Bi were used to impact the DFFs circuit. The results show common DFF has the worst cross section, which is 3.5×10⁻⁸ cm²/bit to 1.7×10⁻⁷ cm²/bit, while TTMR-DFF600 has the best cross sectionof 5×10^-11 cm²/bit to 7×10^-10 cm²/bit, which is only 0.1% of common DFF’s cross section. The six DFF structures were analyzed from speed, area, number of transistors and performance of SEU-hardened. Some meaningful suggestions have been provided for the design of SEU-hardened VLSI circuits.