Due to the high-speed and heavy-load characteristics of aero engine gear, vibrations and noise are often produced, along with engagement and disengagement impacts. These factors can lead to various failure modes and the tooth surface contact fatigue is usually the primary failure mode. By making minor adjustments to the tooth surface, the relevant impacts during engagement and disengagement can be reduced. For that reason, this paper focuses on the modification of tooth profile at the tip and calculates the optimal amount of modification for the gear through theoretical analysis. Further, a parametric simulation of the tooth tip profile modification is established and the Kriging surrogate model is used to optimize the optimal modification curve and the tip rounding parameters. The relevant results indicate that the maximum contact stress on the tooth surface is reduced by 23.57% and that the transmission error during engagement and disengagement is significantly improved compared to the unmodified gears.