The results of modeling railway rails rolling, which are given in open publications, differ significantly from each other. The simulation showed that reason for discrepancy is difference between the initial and boundary conditions accepted by the researchers, which makes their determination relevant when simulating rolling of rails in universal mills. The simulation of railway rail rolling process in universal mill finishing pass has been carried out. To calculate temperature fields and energy-power parameters, the Deform-3D software package was used. Due to absence of the chosen 76HSF rail steel in standard library of parameters Deform-3D software package, a database of its properties was created for this steel grade, including the hardening curves. As boundary conditions, it is assumed that the deformable metal is incompressible and has rigid plastic properties; the material of rolls is absolutely rigid; ambient temperature in workshop t = 20°C. As the initial conditions, the constructed 3D models of rolls and rail were used with appropriate dimensions and saved in the STL format. To reduce the calculation time of a rail, a grid of 102264 elements and 19849 nodes was used. When setting the initial conditions, the rotation of vertical rolls through the moment transmitted to them was taken into account, which had the most reliable effect on calculation results and proved the rail bending effect in the transverse direction. The rolling simulation reliability depends on completeness and quality of setting initial and boundary conditions, including rolling reinforcement, rolls material, friction conditions and thermal diffusivity, as well as speed and dynamic conditions of rolling. The results of study showed that the Deform-3D system makes it possible to create both initial conditions with large amount of data and boundary conditions of various parameters that maximally reflect the nature of one or another MDM process