Abstract: Theoretical physicists predict that there is an island of stability in nature according to the nuclear shell model, but so far there is no evidence for the existence of super-heavy nuclei. In the paper, a highly sensitive measurement method for super-heavy nuclei ²⁹⁸Fl with accelerator mass spectrometry (AMS) was developed, which mainly included the selection of experimental samples, the determination of ionic extraction form, the transmission and measurement of super-heavy nuclei and the monitoring of the system stability. The count is zero for each measurement of super-heavy nuclei ²⁹⁸Fl. The theoretical calculation result indicates that the upper limit of the number ratio of super-heavy nuclei ²⁹⁸Fl and Pb in lead samples is on the order of 10^-12-10^-14.