Abstract: Fluorophlogopite machinable glass ceramic was drilled with tungsten-cobalt carbide and high-speed steel drill bits respectively. Mild steel was drilled with tungsten-cobalt carbide drill bits to compare wears of tools. Machining experiments were carried out on driller with fixed feed load. Tool worn surface were observed with SEM and three-dimension optical microscope. Wears on tool major flank were measured with optical microscope. EDS spectrum was processed to test the compositions of adherence on tool wear surface. Wear processes, wear forms and reasons of tool wear are analyzed. Results show that higher tool wear is obtained in glass ceramics drilling compared with mild steel drilling processes. Because of higher wear, highspeed steel drill bits are not suitable for drilling of fluorophlogopite glass ceramics. Wear of tungsten-cobalt carbide drill bits occurred on major flank, minor flank and chisel edge. Remarkable characteristics during machinable fluorophlogopite drilling process is existence of wear on minor flank. Abrasive wear and adhesive wear are the main reasons for the formation of tungsten-cobalt carbide tool wear. Breakage damage of cutting edge is the abnormal wear form of carbide drill bits.