Abstract: After impact testing, it was found that 5 teeth of the transmission bevel gear of a certain optoelectronic stabilization platform fractured. The reasons for the fracture of bevel gears were analyzed using macroscopic observation, scanning electron microscopy and energy spectrum analysis, chemical composition analysis, metallographic examination, hardness testing. The results show that the gear teeth were hardened, led to an increase in gear brittleness. During the vibration test, fatigue damage occurred at the root of the teeth that engaged with the large gear. Under subsequent impact loads, the fatigue damage rapidly expanded, led to overload fracture of the gear. Changing the surface hardening process of gears, adjusting the effective hardening layer depth of gears to make them have the characteristics of external hardness and internal toughness, or increasing the tooth width and modulus of small gears to improve the bending fatigue strength of small gear roots could all avoid gear cracking.