Abstract: Potassium titanate (K₂Ti₆O₁₃) nanowhiskers were successfully prepared from electric furnace molten slag with titanium by a hydrothermal method with alkaline solution, then refluxing in an acid medium and finally calcination. The effects of titanium-to-potassium mole ratio, calcination temperature, reaction time and water immersion on the crystal phase and morphology of as-prepared products during the calcination process were investigated in detail by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray fluorescence. It is found that one-dimensional single crystalline metatitanic acid nanorods with uniform size are obtained when the hydrothermal reaction is controlled at about 200℃ for 24 h in a 12 mol·L^-1 potassium hydroxide solution. The purity, the crystallinity degree and the aspect ratio of formed potassium titanate whiskers are improved with increasing titanium-to-potassium mole ratio from 1.50 to 1.75, calcination temperature from 800 to 1100℃, and reaction time from 0.5 to 7 h. The optimum conditions for preparing potassium titanate nanowhiskers are the titanium-to-potassium mole ratio of 1.75, the calcination temperature of 1100℃, the reaction time of 5 h, and the water immersion time of 2 h.