The temperature dependence of magnetization in Pr6Ni2Si3 and Pr5Ni2Si3 compounds has been studied with the objective of providing a theoretical understanding of the behavior of the magnetic properties of the material. The ternary Pr–Ni–Si system contains the homologous series of compounds R(n+2)(n+1)Nin(n−1)+2Sin(n+1), where R is a rare earth element which provides a range of materials with different but related structures. The crystal structures and unit cells of Pr6Ni2Si3 (n=2) and Pr5Ni2Si3 (n=3) compounds are closely related consisting of an overall hexagonal structure comprising trigonal columns of atoms, in which the only difference is in the size of the triangular base of the column which depends directly on the chemical composition, specifically the index n. The calculations were based on a nearest neighbor exchange interaction approximation under two kinds of conditions: collinear and noncollinear magnetic structures. The results of these calculations show the Curie temperature, but do not yet predict quantitatively the spin reorientation transition at lower temperatures.