Perovskite lanthanum mangantites La0.825Sr0.175Mn0.9(Fe1-xNix)0.1O3 with x = 0; 0.5; 1 has been successfully prepared with the sol-gel method. The XRD pattern shows that all samples are single phase with no impurities. The result of refinement measurements using the Rietveld method showed that the samples formed rhombohedral with group space R-3c. the addition of doping concentration (x) does not change the crystal structure, but only causes a decrease in lattice parameter, unit cell volume, increases Mn - O - Mn bond angle, and changes the length of Mn - O bond. The Goldschmidt tolerance factor (τ) is calculated to define the stability of the crystal structure. It was found a little uniqueness of the calculation that the τ obtained for all samples has a slight difference with the reference of the τ. In the reference of τ, for the value of τ < 0.96 the material will have an orthorombic structure. Whereas for 0.89 < τ < 1, the material will have a rhombohedral structure. However, in the material La0.825Sr0.175Mn0.9(Fe1-xNix)0.1O3 it was found that the structure formed was rhombohedral with τ = 0.847 - 0.876. This is because the material is in the orthorhombic and rhombohedral phase transition regions.