The composition‐induced crystal structure transformations in the (1−x)CaTiO3–xLaAlO3 microwave ceramics were studied by X‐ray powder diffraction. Increasing LaAlO3 content results in two‐phase transitions: Pnma→Imma (0.4<x<0.5) and Imma→R3c (0.5<x<0.6), which are related to changes of the octahedral tilting: a−b+a−→a−b0a− and a−b0a−→a−a−a−, respectively. The compositional variation of the parameters of the primitive perovskite unit cell is consistent with a continuous character of the Pnma→Imma phase transition. In the case of the Imma→R3c crossover, a discontinuity in the variation is observed.