The invention discloses a method for eliminating the first ten-wafer effect of a flash annealing machine. The method comprises the following steps: S1, arranging a first wafer into a process chamber; S2, heating the first wafer via a flashlight above, and preheating the first wafer at a first temperature via a halogen lamp below; S3, idling the flash annealing machine, and continuously preheating the first wafer at a second temperature via the halogen lamp; S4, arranging a second wafer into the process chamber; and S5, heating the second wafer via the flashlight above, and preheating the second wafer at the first temperature via the halogen lamp below. According to the method, when the flash annealing machine is idle, the halogen lamp is continuously adopted for preheating at the second temperature, and the energy generated by the second temperature of preheating is 50-100% of the energy generated by preheating the second wafer with the halogen lamp at the first temperature, so that the process environment in the chamber can be stabilized, the product yield can be improved and the waste of human resources can be avoided.