Abstarct: Single fiber pull-out test from cementitious matrix has been used to study the post-cracking behavior of fiber reinforced concrete. In this project, the effects of different geometrical properties of twisted steel fiber on the behavior of fiber pull-out from cementitious matrix has been investigated by FE analysis (ABAQUS). Properties such as: equivalent diameter, pitch, cross sectional shape and embedded length have been considered in this study. For simulating the mechanical behavior of steel fiber and cementitious matrix, nonlinear isotropic and kinematic hardening model and concrete damage plasticity model were used, respectively. Stress-strain relation which is offered by Thorenfeldt, Tomaszewicz and Jensen were used for uniaxial compressive behavior of cementitious material. Uniaxial tensile behavior of cementitious material was considered as bilinear. Isotropic Coulomb friction law and basic Coulomb friction model, which is available in ABAQUS, were used to simulate the frictional behavior between fiber and interfacial transition zone (ITZ). Pull-out force-slip curves for twisted steel fibers showed, when the cross sectional shape of twisted steel fiber changes from triangular to octagonal, the slip-hardening behavior is improved. In addition, by changing the shape of primarily polygonal cross section of twisted fibers, which the sides are concave; from primarily triangular to primarily octagonal the slip-hardening behavior is retrieved. In twisted steel fibers with imperfect primarily triangular and tetragonal cross sectional shape that their difference with primarily triangular and tetragonal cross sectional shape are in sharp corner, when the imperfection percentage increases from 60% to 80%, the pull out behavior changes from slip-softening to slip-hardening. Other factors that cause improvement in slip-hardening behavior is increase in the pitch and the equivalent diameter of fibers. Obtained results from suggested model are in good agreement with the test results and showed adequate accuracy.