A new method is employed to study the radiation forces on a transparent plate illuminated by a Gaussian beam under geometric optics model. Unlike optic traps, it depends only on the deference of light pressure to produce the optical lift. According to the law of conservation of momentum, the formula is derived on the basis of angular spectrum theory. The influences of waist radius, transparent plate location and inclination angle are investigated and the distributions of forces are illustrated in longitudinal and transverse components. From the graphical comparison, it is shown that the radiation forces become larger with the waist radius, the distance between transparent plate and the waist radius decreasing. The longitudinal force arrive at the maximum value when the inclination angle is 60°, and the direction always keeps along the z axis. While the transverse forcees along both the positive and negative directions go up to the peak at 70°. The numerical results show that if we choose the appropriate parameters there will be enough transverse forces to conquer the gravity force to move the plate upwards.