The solid solution limit of Pb1-xSrxTiO3 was determined in the composition range of 0≤x≤1.0 at room temperature (RT). The phases 12x x 3 were isolated and indexed in a tetragonal system with x<0.5 and in a cubic one with x≥0.5. The cell parameters of Pb1-xSrxTiO3 continuously, but nonlinearly, change with solubility x. The intrinsic thermal expansions of the solid solution compounds Pb1-xSrxTiO3 (x=0, 0.15, 0.20, 0.50, 0.90, 1.0) were obtained in the temperature range from RT to 1173K with high-temperature X-ray powder diffraction. Negative thermal expansion coefficients of Pb Sr TiO (x=0, 0.15, 0.20) were found below the Curie points. The thermal expansions of these titanate ceramics were highly correlated with the solubility in the solid solution Pb1-xSrxTiO3.