Composite steel/concrete girder is one of the main structural systems used in bridges and buildings. Steel element mainly located in tension zone and a concrete element located in compression zone. Full integration by the shear connectors used to simulate as one section without any slippage between the two materials. The classification requirements for steel sections and composite sections in most specifications were originally derived from experimental and analytical studies based on the theory of elasticity. The compression concrete slab restrain the buckling of the top flange and the compressed part of the web. Steel plates behave plastically up to failure. By considering concrete slabs connected to the steel compression elements, the section may be placed in a better class in terms of slenderness. The present study focuses on the evaluation of section classifications using ANSYS (FE- software). An extensive parametric study using the calibrated FE modeling procedures was preferred to predict the modified relaxed equation. A new released equation and new classification limits have been developed between compact and non-compact considering the fixity effect of the concrete slab. In this study, yield strength of the steel material is 2.4 ton/cm2 and concrete strength 0.20 ton/cm2.