The coolant reduces the grinding temperature and prevents the grinding wheel wear. The wear of grinding wheel, especially in the formed grinding to the difficult grinding materials, is disliked for the preservation of the exact size of the workpieces. So the new coolant nozzle which is named floating nozzle has been developed to decrease the grinding temperature and the wear of superabrasive grinding wheel. The new nozzle consist of the graphite and is pushed to the grinding wheel by the weak rigidity of spring. When the surface shape of the top of nozzle becomes the same as the circumference configuration of grinding wheel, it will have floated and separated from the grinding wheel owing to the pressure of grinding fluid. Therefore the narrow gap between the grinding wheel and the nozzle is made and the grinding fluid adheres to the wheel. Then the new nozzle cuts off the airflow around the grinding wheel and the adhered coolant is always supplied just to the grinding point. In the result of experiment on grinding SiC and Si3N4 with the new nozzle, it showed the high performance of grinding ability on the dressing interval, the specific grinding energy and the surface roughness.