A new method was studied for measuring the shape of transparent objects by image processing based on polarization analysis on reflected light from the object surface. Polarization characteristic of reflected light from transparent object surface was studied and it shows that reflectivity varies with direction of reflected light while natural light is reflected via transparent surface object, i.e., the reflection will exhibit characteristic of partly polarized light. The relations of intensity reflectivity and incident angle and intensity and polarizer direction were studied, and the relation between reflectied intensity and incident plane orientation was deduced. The relation of polarization degree of reflected light and incident angle was established based on definition of polarization degree, considering Fresnel equation and reflection law. Thus the surface normal direction can be determined and the shape of transparent object is obtained. Polarization images were taken experimentally and three-dimensional shape of object was reconstructed by image processing. Experimental results show that the proposed method is effective and valid for shape reconstruction of transparent object.