Calcium-doped titanium dioxide (TiO2) precursors were prepared by the direct hydrolysis and precipitation of titanium sulfate (TiOSO4) and calcium hydroxide, (Ca(OH)2) and then calcined. The phase-transition temperature, crystallinity, crystal size, specific surface area, phase composition, and photocatalytic performance of each sample were investigated. Calcium doping was found to inhibit the phase transformation, crystallinity, and grain growth of TiO2, and improve the photocatalytic performance of the precursor sample because Ca2+ has a larger ionic radius than Ti4+. Cell growth is greatly hindered when Ca2+ enters the TiO2 cell, which increases the phase-transition temperature and the specific surface area while decreasing grain size and crystallinity, thereby improving photocatalytic performance.Graphical Abstract: