The present invention relates to an optical transformation device, and more particularly to an optical transformation device able to transform a projected light beam from a spot light source to form rectangular projection surfaces, which primarily includes a refracting body composed of an emergent surface structured from a combination of a plurality of optical surfaces and an incident surface configured as a concave spherical surface. Two reflecting surfaces located at two sides of the meridian of the emergent surface enable the luminous flux of incoming light to completely impinge upon the refracting body, and the interactive effect from the combined optical surfaces transforms the light shape of a light beam from a spot light source, and is projected to produce an almost rectangular shaped illumination projection surface.