Abstract: Applying TCA(Tooth Contact Analysis)and LTCA (Loaded Tooth Contact Analysis) techniques,the influence of pitch error on the meshing behavior of aviation spiral bevel gears with contact ratio 2 0 was studied.First,the relative pitch error was defined and its amount was selected according to the accuracy degree of aviation gears,then the influence of this error on the real contact ratio,transmission error,load distribution on tooth surfaces and load share between teeth was analyzed numerically.Further,the effects of load changes under certain pitch error and pitch error changes under certain load were analyzed to provide conditions for application of aviation spiral bevel gears with high contact ratio.