Calcium ferrite (CF) is the significant liquid phase for fluxed sinters, which are the main iron‐bearing materials charged into a blast furnace. The isothermal reduction kinetics of CaO–Fe2O3 (0, 2, 4, and 8 wt%)–Al2O3 (CF, CF2A, CF4A, and CF8A) by CO at 1073, 1123, 1173, and 1223 K are investigated by thermogravimetric analysis in this study. Results indicate that temperature exerts more influence on the reduction degree of ternary CaO–Fe2O3–Al2O3 system than alumina content. The reduction processes of CF, CF2A, CF4A, and CF8A are mainly expressed as a typical two‐stage reaction. The apparent activation energies of the reduction of CF, CF2A, CF4A, and CF8A are 43.6, 97.9, 87.7, and 82.9 kJ mol−1, respectively, based on the model‐free method. According to Sharp analysis, the reduction of CF is described by the Avrami‐Erofeev equation with 2D reaction, that of CF2A and CF4A is expressed initially with 2D reaction and then by the 2D phase boundary controlled reaction, and that of CF8A is controlled by 3D reaction.