For growth tube and star like structure of Si wafers and Si epi wafers,thetranditional method of test defect is chemical corrosion.Using this method,the sample will be destroyed.A new method is introduced for the detecting test of growth tube and star like structure,that is magic mirror (MM).The MM approach has been proven to be a very simple,non destructive and effective techniques with high sensitivity to test various flaws on mirror like surface.The resultsis in agreement with chemical corrosion.