In this study, effect of varying opening location and size on the punching behavior of two-way RC flat slabs was investigated through the finite element analyses. For this purpose, the two-way RC flat slabs with openings in the literature done by the authors were simulated using finite element modeling technique. The variables that were investigated in the study are the location and size of the opening. For the study, two-way square slabs having the dimensions of 2000 x 2000 x 120 mm with openings were analyzed. The nonlinear analyses were performed using the ANSYS FEA software with reference to the experimental data. The experimental results were compared with the finite element analyses results. According to the results of this study, it was shown that when properly modeled, finite element simulations may be used as efficient tools for estimating the nonlinear behavior of flat slabs with openings subjected to punching capacities. Simulations performed using verified finite element models estimated the punching shear force capacity of the flat slabs with variable openings with 7% average error. Moreover, the load-displacement relationships of the specimens are estimated in good agreement with their experimental counterparts.