This paper presents our researching results regarding numerical calculus by Finite Element Method (FEM) of the Functionally Graded Plates (FGP). Two approching ways were used: the concept of multilayered plate and the concept of equivalent plate. By using of the multilayer plate concept, the continuous variation of the material law is replaced by a step variation; the layers have homogeneous and isotropic properties, with values established according to the methodology presented in this paper. When the equivalent plate concept is used, the FGP is replaced by a completely homogeneous and isotropic plate, but with fictitious properties that lead to a behavior similar to the real plate. The significance of the study consists in the elaboration and presentation of the FGPs calculus models, which can be approached with the existing current means, available to any researcher. The aim of this study is to enrich the knowledge regarding the numerical calculus, with the finite element method, of the FGP, using the current general knowledge and software products. The objectives of our study were to develop models and methodologies for calculus by FEM, available immediately. The results of the numerical simulations were validated by comparison with the adopted analytical solution. The use of the Ansys program, with the general options, available in many professional program by FEM, is still a reliable element in the numerical results and the validation of the results of our study. The methodologies, observations and conclusions are valid for any of these material laws presented in this paper.