Plate-like α-Al2O3 particles are used to reinforce metal or ceramics to improve their mechanical properties. Here, we have demonstrated the production of alumina platelets using kaolin as a raw material in a sodium sulphate flux. When kaolin was sintered using Na2SO4 flux, the main phase formed in samples sintered at 900°C was mullite, but alumina was produced at 1000°C. Sintering at 1200°C led to alumina and sodium aluminosilicate, with little of the mullite phase present. Plate-like α-Al2O3 particles were observed in samples sintered at 1200°C, with diameters ranging from 1.5 to 4.5 μm and thicknesses from 0.05 to 0.1 μm. This production method is economically feasible because the raw materials have a low cost and the sintering temperature is low.