Comparative analysis of involute cylindrical gear strength rating methods used by ISO standard and AGMA standard was conducted.Gear parameters and derating factors were classified.Differences between the meaning and selection of gear parameters and derating factors,as well as their effects on gear rating results,were analyzed through calculations.The study indicates that neither of the two standards is more conservative than the other one, and the bending strength rating results of AGMA standard are more sensitive to the change of gear geometry parameters.The study also indicates that different values of parameters and derating factors cause the differences in gear rating results of the two standards.The allowable stress number,load,geometry parameters and life have the most significant effects on pitting resistance rating results; while the stress correction factor relevant to the test gears, load and geometry parameters have the most significant effect on bending strength rating results.