A new micro single flute drill was presented in this study. For the convenience of developing a solid model, and doing a geometrical analysis, its geometry including the flute and flank surfaces is presented mathematically. According to the geometrical analysis, the normal clearance angles and normal rake angles along the cutting lip of the new micro dill are always invariant, and positive, respectively. Hence its cutting force in drilling is reduced. Furthermore, with only one main flute, the new micro drill gets stronger, and its cutting torque can be also decreased. Therefore it is expected that the tool life of the new micro drill is much longer than that of the conventional drill.