Abstract: Fe-CuMnNiAl steel was quenched to room temperature and then tempered at 450℃ for 4 h. The tempered steel specimens were tested by three-dimensional atom probe (3DAP) under voltage mode and laser mode respectively to study the effects of different modes on the test results. The results show that the background of the data was smaller, the mass resolution was higher, the composition analysis results was more accurate under the laser mode compared with those under the voltage mode. Under the laser mode, the divalent evaporation ions were reduced, while the monovalent ions increased, and two atom group evaporated at the same time even more. It is found that the precipitate was bigger in size and was slightly lower in density under the laser mode than under the voltage mode, and the core Cu content of precipitate was lower under the laser mode.