The invention discloses a method for preparing calcium fluoride and potassium bicarbonate from carbon dioxide, and belongs to the technical field of phosphorus chemical industry. The method comprisesthe following steps: (1) reacting potassium fluosilicate with a potassium-containing compound to obtain a crude potassium fluoride solution and silicon dioxide; (2) adding fluosilicic acid into the crude potassium fluoride solution to adjust the pH value in order to obtain a potassium fluoride solution and a silicon dioxide-potassium fluosilicate solid, and returning the silicon dioxide-potassiumfluosilicate solid to step (1); (3) acidifying a calcium hydroxide emulsion with carbon dioxide to obtain a calcium bicarbonate solution; (4) reacting the potassium fluoride solution with the calciumbicarbonate solution to obtain the calcium fluoride product, and treating an obtained filtrate to obtain the potassium bicarbonate product; and (5) drying and calcining the potassium bicarbonate mother liquor to obtain potassium carbonate, and returning the potassium carbonate to step (1). Byproducts which are a fluorine potassium phosphate compound and fluosilicic acid and am ammonia synthesis byproduct which is carbon dioxide are processed by only using calcium hydroxide and a small amount of the potassium-containing compound to form high-value calcium fluoride, potassium bicarbonate and silicon dioxide.