Abstract: In order to clearly observe the intergranular oxidation of materials and accurately measure the depth of intergranular oxidation, samples were prepared by hot and cold mosaic methods. After sample grinding and polishing, the edge morphology of the sample was observed under optical microscope to select the optimal sample preparation method. The results show that in the process of grinding and polishing the sample, the edge of the sample should be protected to avoid scratches and fillets.