The paper presents numerical results of direct pull-out test of glass fiber-reinforced polymer (GFRP) rebars embedded in concrete. Rebars of three different cross-sections are considered: circular without longitudinal ribs and with two and four ribs. The design analyses of the rebar configurations embedded in concrete are investigated by the 3D finite element method (FEM), which takes into account the non-linearity using ANSYS software. The results of the numerical model with two ribs were compared with the experimental results. Then, the effect of different rebar's geometries to the load-slip pull-out curves was studied. It is concluded that the influence of rib height and width in the rebar with 4 ribs much higher than with 2 ribs on the pull-out load.