Composite resins has been widely used in dental clinics because of esthetic restoration. The aim of this study was to assess the effects of the cavity designs on the compressive stress of resin restoration. So, the author made the standardized specimen of four types (Type of speciemen are width 1.5mm, depth 2mm, width 1.5mm, depth 3mm, width 2mm, depth 2mm, width 2mm, depth 3mm). The compressive strength was measured by universal testing machine (Tong Kwang Co.) The results indicating following; 1. There was a statistic significance of compressive strength between four cavity forms. 2. There was no difference of significance of compressive strength between two resins. 3. There was a significance of compressive strength between depth 3mm width 1.5mm and depth 3mm width 2mm.