The aim of making line structure in railroad is to provide the safe and economic passage of trains. This requires an appropriate performance of line as a sustainable path with discipline in both horizontal and vertical alignments. The line is subjected to dynamic loading exerted from train. Hence every element of the line system should respond to the traffic loading properly. In this case the subgrade soil as a support under the slab track plays an important role in stresses and vertical displacements. Concern should be given to these kinds of displacements since they can endanger the safety of the motion and induce noise. Therefore, in the analysis, estimation of these displacements are important. Because of the engineers requirements to a rapid estimation of stresses and displacements in concrete pavements with express train system, some analyses should be done to display effect of the type of the soil and the concrete slab in the stresses and displacements. Here, this effect is explored through a parametric study on the type of the concrete, the dimensions of the slab tracks and different types of soils (from very weak to very dense ). In the most of studies, the behavior of soil is modeled with linear Winkler springs. However it is necessary to consider the nonlinear behavior of soils to study the effects of nonlinear deformation in design of slab tracks. To recieve this goal, in the first step, the result of linear Winkler springs and combin14 element are utilized and in the second step the BNWF model and combin39 element are used. This model applies the effects of dimensions (length, width and thickness) and shape of slab in the stiffness of soil and presents the diagram of behavior of soil in nonlinear shape. In this study, a set of the pavement including rails, fasteners, slab tracks and line infrastructure (subgrade soil) are modeled with appropriate elements in ANSYS Software. The results show that the type of concrete, behavior of the soil and dimensions of slab track are three main terms in determining the stress level (force and bending moment) and displacements in concrete. According to the results, stresses and displacements in transverse direction are higher in comparison with longitudinal direction and the negative transverse moments cause cracks in slab. It was also an objective to balance positive and negative moments in order to increase the capacity of slab tracks and make a better design. From the results, in prefabricated and insite made slabs, 2.4 meter in linear and 2.3 meter in nonlinear behavior of soil are derived for the optimum width of slab. Also in the semi dense soils, the length of 4.8 meter and thickness of 20 centimeter for slab is suitable for train loading. At the end of this study, the way of changing in the cracking load and the ultimate collapse load based on the type of the subgrade soil and concrete compressive strength is derived for the slabs with 2, 2.3 and 2.5 meter width. Keywords :Concret Slahy;Track, Winkler Springs, NonlinearBehavior, BNWF Model, Cracking Load, Ultimate CollapseLoad