Selective laser sintering (SLS) of polymer powders involves multiphysical transient phenomena. A numerical tool for simulating such a process is developed on the basis of the reliable modeling of the corresponding thermo-physical transient phenomena and appropriate numerical methods. The present paper addresses modeling, simulation, and validation aspects that are indispensable for studying and optimizing SLS process. The coupled multiphysical models are detailed, and the numerical tool based on the finite volume method is presented, with validations in terms of numerical and physical accuracy, by considering the shrinkage involved in the process and the successive layers deposition. A parametric analysis is finally proposed in order to test the reliability of the model in terms of representing real physical phenomena and thermal history experienced by the material during the process.