Tubular structure system is one of the most suitable structural form of tall buildings. When it is subjected to lateral forces, columns in two opposite sides of neutral axes response as tensional and compressive. also, the parallel frames for the lateral side are under the influence of the bend on the plate and the shear or tread behaves like a rigid frame. In addition to flexibility of peripheral beams, this mechanism causes shear lag and increases stress in corner columns and decreases stress in middle columns in flange and web panels. Purpose of this thesis is to investigate the effects of the use of brace on the shear lag, for this reason for evaluating results of structural analysis, dimensionless parameters as shear lag indexes are used. For probing effects of different braces on shear lag index, each and every one of braces in four mid-opening is put as base and then it is put as base in all peripheral openings of structure. Results indicate that using braces had a positive effect on shear lag index in higher stories, as using braces in all spans, causes steady reduction in shear lag index in higher stories and also decreasing negative amount of shear lag index in this case is lower compared to four mid-span model. At the end considering the results it can be perceived the best type of braces, between braced systems is X-braced systems according to decreasing amount of shear lag index and story displacements.