A parametric study on the punching strengthening of reinforced concrete two-way opened slabs using a carbon fiber reinforced polymer (CFRP) sheet is presented. Thirty-six reinforced concrete (RC) square slabs of 100mm thickness were analyzed over simply supported four sides of 1200mm span under central square patch load of 100mm size up to failure. The parameters under this study are opening location, opening shape, number and size of the opening, CFRP sheet width, CFRP sheet thickness, fiber orientation, and position of CFRP sheet application. One control slab without opening and strengthening. Twenty slabs with an opening but not strengthening and fifteen slabs with an opening and strengthening RC slabs were analyzed using ANSYS 2021.R2. The accuracy of the FEA method was verified using experimental test results in the literature. In terms of ultimate load and crack pattern, the FEA results were compared and showed good agreement with experimental test results. Generally, opening reduces 22.03% to 31% of the ultimate load of the slab. After strengthening, up to 17.03% and 69.6%, the ultimate load is recovered beyond the control slab and opened slabs respectively. The stiffness and ductility of the slab have been enhanced in this study. Generally, this research presented a practical strengthening using the finite element method concept that can be used to increase the punching shear capacity of two-way opened slabs. Therefore, we can use openings within 6d and 4H without adding loose reinforcement. However, strengthening using CFRP material is applied carefully. Keywords; CFRP sheet, ultimate load, drop in ultimate load, restored ultimate load, ductility, stiffness