The stress analysis of the double column made of the dissimilar material is not enough reported the problems about the interface of the crack on the surface. These products are guaranteed for the high performance, and are composed of the dissimilar material or composted to the new material or composed to the new materials again by the compound of the material and the advancement of joint technology. The Stress Intensity Factor K, Kand K usually act in single or mixed modes. The separation of K, Khas already been achieved. In this paper, an experimental technique for determining the stress intensity factor Khas been presented by using the method of reflected caustics in combination with the stress freezing method. The experimental model is a cylindrical bar with w radial crack along the direction of the axis under the load of pure torsion. In order to obtain a caustic pattern, a slice cut from the frozen model is annealed, and evaluated it for the stress intensity factor in a double column of the different kind material by the experiment analysis.