Scleral flap preparation is one of the basic operations in glaucoma surgery including trabeculectomy, glaucoma drainage implants (GDIs), and canaloplasty. In most cases, scleral flap preparation is performed manually by surgeons based on experience, which is various from person to So far, few robot-assisted scleral flap operations are applied. In this paper, a scleral flap drilling system is developed by integrating a force/torque sensor and an arc-shaped drilling tool. The drilling tool is designed based on a corneal trephine. The maximum force and torque are derived theoretically. Scleral flap preparation experiments are then performed on cadaveric porcine eyes. The maximum vertical cutting force and the difference of two continues peaks of torque are recorded and analyzed under various linear and angular velocities, and an empirical polynomial model is used to fit the correlation between the penetration force and the cutting depth. The results show that the maximum vertical cutting force and the penetration force occurred at different location. About 95% of the penetration force is observed below 2 N.