As a finishing of the gear, the gear honing is offten used recently. However, it becomes urgent that we extends the grinding wheel life and lowers the cost for the processing. This paper describes the effect of gear ratio between work gear and grinding wheel on the tool life, when the fixed crossed axes angle system was adopted. First, when the dressing was repeated, the difference of accuracy of work gear tooth profile in two gear sets with different gear ratio was shown by processing experiment. Considering from the viewpoint of skew gear, the change of the form of contact lines at every dressing is different between two gear sets, and it was proven that this gave great difference to the change of the tooth form accuracy of work gear.