For the problem of the fast tool wear and low processing efficiency for SiCf/SiC ceramic matrix composites ith dry drilling, an ultrasonic vibration assisted dry drilling processing method with the brazed drill of defined grain istribution is proposed. The brazed diamond drill with different defined grain distribution parameters is used to drill the iCf/SiC ceramic matrix composite w th the ultrasonic vibration. By the measurement of the machining holes, the influence aw of the defined grain distribution parameters on the tool life and the size of the hole accuracy are studied, and the abrasive ear characteristics at different positions of the tool are analyzed. The results show that the longer service life with the ore grins in the tool end surface. The longer and the more number of columns abrasive grain layout of the tool side, the maller changes for the pore size of the holes. The nearer the abrasive distance to the end of the tool, the more serious the brasive wear is, and the main wear is the wear platform and the macro breakage. The farther the abrasive distance to the nd of the tool, the less wear of the abrasive is.