Nowadays, the composite of steel and concrete is quite popular but it is also important to improve and develop the structural systems especially the construction and design of wooden structure. Furthermore, wood components would reduce the risk of buckling on individual activity of steel and thus leads to more efficient hybrid steeltimber structural systems in the future. As traditional way, designing a beam has been simply achieved and the geometry of the timber-steel-hybrid beam is really ideal advantageous to improve their work. According to the first generation of timber-steel-hybrid beams called “Flitch-beams”, the aim of this study is to follow and develop a method in order to provide high load carrting performance for these kind of composite beams. Basing on the main concept of data tables from National Association of Home Builders of the United States (NAHB) builders’ beam showing the capacity of Flitchbeams with variety sizes, this study chooses one fixed pattern of 2 wood pieces (2x8’’) inserts by a straight steel-platecore to evaluate and the optimized morphology among the variety cross-sections is then applied in to the beam as replacing for straight steel-plate-core. The result shows that the comparison relies on numerical of Maximum bending stress (s) and deflection at mid span. Following this, the new flitch beam is re-calculated and the results in comparison with the NAHB builders’ beam pattern. Similarly, the final result indicates that the coordination of optimized steel core is more advantageous than the pattern beam.