The difference of bevel gear strength rating methods between ISO standard and AGMA standard is analyzed and compared. The meaning of correction factors and differences between the two standards are analyzed through classifications and examples,and the gear parameters effects on gear rating results are also analyzed. The study indicates that it is the different values of parameters and correction factors that cause the differences in gear rating results of the two standards,and the load,geometry parameters,material property and surface condition have the most significant effects. The AGMA standard tends to be conservative in the calculation of contact strength,whereas ISO standard tends to be conservative in the calculation of bending strength.