The structural performance of a T-Composite CFS Beam and a Concrete Slab was investigated using Finite Element Analysis. In this study, eight experimental composite beam specimens were validated, and ninety-six Finite Element models were evaluated under flexure. Three cross-section shapes (T, Y, and R) were studied. All parts have a monosymmetric steel cross section that connects to a 1000 mm wide concrete slab. The current study seeks to evaluate various cross-section modifications, such as CFS form, beam depth, flange width, slab thickness, and beam span. All models were tested using four-point loading and simple support conditions. The section failure modes and load capacity of all specimens were determined using FEA data. It has been observed that the verified models' results have a very good agreement. Additionally, the new parametric study results showed that the Y-shape could be better than the R-shape and T-shape because of the presence of the filled top flange, which causes more stiffness for the section and increases the section load-carrying capacity by 28% more than the T-shape. Changing parameters such as increasing slab thickness could enhance the section load capacity by about 42%, 9% for changing beam width, and 51% for increasing beam depth.