Slicing process plays a very important role in layered manufacturing technology. A slicing algorithm decomposes the 3D CAD model into 2D layer contours that can be easily built. This paper presents a new adaptive slicing algorithm for a rapid prototyping system. According to this algorithm, the 3D CAD model can be sliced with different thickness automatically by comparing the contour circumference or the center of gravity of the contour with those of the adjacent layer. The part can be fabricated faster using this adaptive slicing method than using the uniform slicing method with identical accuracy. The proposed method was validated with computer simulation, and the part can be produced on the developed LCD panel display based rapid prototyping system.