This paper introduces some results of grinding test for decreasing grinding time in gear grinding. A prototype developed by the authors and an electroplated CBN worm of double threads were used for the test. To know whether high speed grinding impairs gear accuracy or not, some grinding experiments were carried out with changing rotary speed of a grinding spindle. And to know whether grinding with deep radial feed and rapid axial feed impairs gear accuracy or not, some experiments were also carried out with changing above conditions. In this case, the gears were ground into the root of the gear tooth for evaluating a performance of a servo controller of the prototype under heavy load. After experiments, it was confirmed that profile errors and pitch errors of the gears ground are very small at 7000 min-1 within a rated torque of the wheel spindle because angular positioning errors of grinding' spindle and workspindle of the prototype are always small enough. Moreover we examined a power consumption of the grinding spindle and cleared that it is in proportion to a removal stock rate of the gear tooth.