To overcome the disadvantage of low contrast in the images taken with the traditional slicing method of reverse engineering, a novel slicing method of reverse engineering based on the principle of refraction and reflection of a prism is proposed to improve the contrast of the cross-sectional images. According to the reflectivity of the object, one of the illuminating methodsstraight illuminating or inclined illuminatingis adopted to get the sharp contrast images of bright object in dark background, or dark object in bright background. To adjust geometrical distortions caused by the refraction and reflection of the prism, a mathematical transformation model is set up to correct the image by means of software. This method has been applied to some cases of reverse measuring. The research confirms that this new slicing method has not only the advantage of high contrast, but also the clear and reliable contours of the cross-sectional images, what's more, there is no need of contrasting filling materials. It is hopeful that this method will play a great role in the reverse measuring of mechanical parts and models.